THE EVOLUTIONOF THE CEPHALOPODA
BY L. F. SPATH,D.Sc.
[Rennrr.rruoeno*r BIOLOGICAL REVIEWS, Vot. VIII, No.4, Octonr.n19331
- CAMBRIDGE AT THE UNIVERSITYPRESS. THE EVOLUTION OF THE CEPHALOPODA Bv L. F. SPATH, D.Sc.
(ReceiaedFebruary zz, 1933.)
(With Thirteen Text-figures.)
CONTENTS. PAGE I. Introduction +r8 II. Distinctions between Ammonoidea and Nautiloidea +2r (r) The initial chambers +2r (z) The coiling 42+ (3) The siphuncle 430 (4) Other characters 439 III. The ammonoid ancestor 4+2 IV. " Bactrites " and recapitulation 445 V. The primitive Cephalopoda 450 vI. The supposed cephalopod Volborthella 4s3 VII. The phylogeny of the Cephalopoda 455 VIII. Thb Dibranchiata 457 IX. bummary 459 References 46o
I. INTRODUCTION. Tun development of the ammonites cannot be discussed independently of the evolution of their Palaeozoic forerunners, the goniatites, and the earlier types of these, again, are very intimately allied to the ancestral nautiloids. Although some- what diffident of casting so wide a net, I feel that the problem of the evolution of the Cephalopoda must be restated. In the past, what in my opinion are erroneous views of the development of the Ammonoidea have been popularisedlargelythrough the enthusiasm of workers who were attracted to the subject but had little practical experience of ammonites, and who too often were inclined to treat these fossils not as the remains of natural organisms but as material for speculation. This article, however, not only criticises the prevalent view that the ammonites, like the ancestral goniatites and Clymenia, arose from a straight nautiloid (Bactrites) and then hurried through the early stages of coiling before uncoiling again towards the end of their career; it also discusses various views put forward by workers on the primitive nautiloids. Yet with the purpose of making the article intelligible not only to the specialist but also to those who have only a slight acquaintance with the subject, I have attempted to illustrate in the text-figureS at least the more important features of the different fossil Cephalopoda referred to in the following pages. snorres n fq peqsrlqnd eg ol crlselueJ oo] tou sB/K slloqs perrnbce ,tltuapuedap -ur pue ,{lpaleodarr{crr.l^\ spodolegdec ssel-llerls Jo uolssecrnsIEnUI}uoc e Jo uol}ou 'passncslp (9z6r) s(ualuur?rqcg uale ag o1 lecrtaqtod.,tqoo1 ag otreuos ,tq pareprs -uor ueeq aABq',ro1eq o1 parraJe: 'sprueurdlcaqr uo s^tell (fr6r) s(.^A.eloqosalI{AA 'ller{s 'putur aql Surueqt8ua:ls;o .,{e.,vrlecruouoce uB .{1e:aurst 1r .{ur o1 ,,'slcnpord Ienxas snourunlo,r dlqeqord aqt eceld o] urooJ eJour Surure8 ;o dlrssacau eql 'uorldrosqe 's11eqs 'd ruo{ ^,(q aq} Jo eprsur ar{} uo paleut8uo,, uol}Elnuue slq} (ozt 'rc6r) uuztuepand ot Surproccy (;so,IarolluO,, lo sLuJoJuleuec Jo uollelnuue 'aldruexa 'se eql Jo esec oqt ur JoJ .,tren,{ew sarnlea; eldurrs ,{1}ua.redde5o uot}e}ard -Jelur eql pu€ lsregtro pue'npaqlnqloA Jo arnleu eHl ,,'sap4tng,, Jo qJuocolo;d '1sr8o1o1uoae1ed er{} are qcns I qooq-lxet eq} .{q Sur8pnf le.reue8eq} o} pel}}asreadde '8uture.t .,reu qcrq.n sturod uo uorurdo5o acua8relrp l{cn{u lills sI aJeqJ . srqt lseSSns leql euole lerrateur er{t Jo 8ur1ep InJtqnop pue arn}eu 1ca;redrurer{} }ou sI }f }ng 'suorlcssurq] 'xuletu ur arnlcnrls leurelur IBaAeror IIeJ dlquqord plno.,ra er{} Jo d1rur1p1s.{rceql 'suerurcads'peqsn-rcun 'a'!'pa.trase-rd 'pecgIJcBS Jo ]unocce uo dlqe-rnoleJlsoru oql 'sJalceJer{c Jr uelg snorlqo ssel aq} go uorle8r}salul palle}ap erour ro3 gSnoue luepunqs Jo elqBlrns sr teql IBrrelB(uou ]sourlB sr eJal{l tBq} PUB-sEunEJ e}IuoururB elrssecrns uaeunoJ slr qlra-porrad }{nep ar{} Jo eloq,a oql ueq} uol}Ernp -ra8uol dlqeredruocur Jo serA-souoz el:rtaruo81n;rqnop o.{a}'t{lr1y\-ueruola0 Je,^.oT sII{} '8ur11eddu'paaput leql repeer 1ecr8o1oa3-uoueql uodn ssardurro1 d:essacousr 1I 'sl 'pap;ocer e8peyvrou{ }cexe Jo {JBI ;no ueeq e^€q sprouourtue lprg eI{} acuarl.^a uerrnlrs reddq eql Jo do1 eqr ro uzruoleq re,{aoTaqr Jo eseqaqt o} u,^aopouroc e.^a uerll6 'sruJoJpolceuuocsrp pue pelelosr uo esle .ro sotcedsu^\ou{ dlereldruocul uo 'Sutsodurt peseq ,{1a8re1ere ,(ag} sesodrnd lecrqde-r8r}€rtsroJ }uellacXe roAo,t\oqtnq eq detu seuoz elrleruo8 snoJeJruoqJ"J Jo suozrJor{ a}ruoururz JrssBrJI Jo Jaqrunu 'suorsseccns (s{ror oqJ paldnr-ralurun pug o1 souroreq U llncsrp erour eq] eI{} 'seuneJ raplo er{J crssernf e8pal.u.ou{rno uI }sIXalprs sde8 }ea-r8}BI{t reerl ol ".ll;o pesud-lns eq deru euros q8noqr 'urvrou>1dlq8no-ror{} ssel re; dlureual sI crssernf aqa 'seune; elruourure olrsseccns dueur os Jo uorlducsap eq] roJ serllunuoddo lenba pro$e lErraleur leco,rrnbeun puB pooS Jo esuePunqB PuE dqderSrlerls Paugar pu? reelJ qclqa ur uorleurroJ snoocelarC ror{}o due sr areql rer{laq.l.rInJtqnop sr }r te^ 'pallos ag of urzurer llrls suelqo.rd .(ueru ,lroq SursrlBeJure I pue uorlerederd ur sr 'sdr1 qderSouour ar{l;o ged qlue^ela eq} ,^aol{ ,sre8ug ,tru }e slrssoJeseqt ;o .,iro1s 'eldurrs eql e^Er{ o1 ;1es.(u pe^orleq I pue .(la.Lrleredurocelord plnorn >lw} eq} }eq} 'rynog luapuuoc sei\rI ary {o oaprouoluuv aLft{o qdorSouow,(ur ;o ged 1s-rgoq} otor.{a to8e tueq11 l s:ee,(ua1 ,,'ctsszrnf,, ol ,,snoec?traJJ,,uro{,,teuecol6,, o} ((aueJ '.,tes 'e}ErqaueA -olld,, tuo.r; sdunf Jrer{}Jo epn}ru8eu agt esrleerslsrSolooz ,Lrag 'slerurue -ur Jo o]BJqeuol Jo suolle1nur elrssocons Sunrasqo Jo esee eql Jo 4zeds 'serJn}uec or{/'t esoq} Jo rusrurrtdo epceg aq} eJ€r{s lou op I uaou{un }uase;der (sao8 ol elq€{ sr le^relur paprocerun dre,ra eJour eql uerro}srq lecrSoloa8 eq} lJeq JoqunJ er{J'relncr}red ur slrssoJrno Jo 8ur1epeql pue 1e-raue8ur aJuorrs lecrSoloa8 'd'p Jo ernl€u a,rrlelncadseql Sururecuoc (toL tt6r) oreq.&\eslepres a^eq J ]Br{1v\ ol acuereJar e ,(q olcruB er{} ecqerd ol Pe^\ollB aq .,teurJ uosBer ourBseq} roc 6* apodopqda3ary {o uolru1oaaaqJ t#/wuu),Q/ 420 L. F. Sparn scientific society. Many observers, bewildered by the seemingly endless r-aria- bility of one small groupr missed the essential uniformity of the ammonoid (or, indeed, cephalopod) stock as a whole. But these examplesmay at least partly explain why the problem of the origin of the Ammonoidea and their relationship to the ancestral nautiloids is still debated. My own views outlined in ry23 (p. 6S), are more or less diametricallr- opposed to Hyatt's Q867-rgo3); and it is attempted in the present article to shou' that some of the opinions expressedby Hyatt fifty years ago and still adopted by certain *'orkers were based on mere conjecture. Thus it is still commonly asserted that (r) the recent IYautiluscan be traced back in an evolutionary seriesthrough spiral gyrocones (Fig. 5 c) and curved cyrtocones (Fig. 5 b) to the straight Orthoceras(trig.5 a). This series is held (z) to be characterised by the absenceof a calcareousprotoconch. Then it is stated (:) that an Orthocera.sin which the (supposititious) protoconch, i.e. initial chamber, had become calcified (instead of being shed) gave rise to a straight ammonoid shell (" Bactrites") with ventral siphuncle. Next (4) this is said to have produced the loosely coiled " Mimoceras" and the involute goniatites which in turn gave rise to the ammonites. Assertion (r ) was a fallacy even in Hyatt's time ; lie himself statedthat there were no such serial relations in time. Assertion (z) was based on an assumption, dis- credited many years ago and now known to be quite untenable.With regard to (3), it can be demonstratedthat every rich Orthocerasfauna (and sometimesa single species) has some forms with marginal siphuncle. (+) " Bactrites" (recteLobohacttites) is a secondarily uncoiled goniatite becauseonly series going from curved or coiled to straight can be demonstrated, never from straight to coiled. When previously ridiculing the notion of a straight Orthoceros stage being " omitted " or " skipped " in IVautilus and the }lesozoic ammonites, I stated my conviction that the first goniatite, namely the Silurian Agoniutites, u'as nrerelv a slightly modified I'{autilus (e.g. Barrantleocera.i),but my immediate concern was a disavowal of the usual palingenetic methods. Since then I have been prornpted to discreditHyatt's " laws" more vigorously,merely as a result of practicalexperience. T'hose who work on other groups may at least be interested to hear s'hat constant handling of cephalopodsfor many years has-rightly or wrongly-suggestecl to nre, as opposedto the theorising of amateursat a distance. If it be objected that special- ists like the late Prof. J. Perrin Smith (tgSr) came to different conclusions, I can only reply that in my opinion he constantly overlooked the fact that by hereclitv an ammonite was an ammonite, and that like other organismsit had to grorv and thcre- fore necessarilyhad to pass through more primitive stages(see Spath, r933 6). The principal conclusions arrived at in the present enquiry are summarised in the final section. Their briefness may invite categoricaldenials, but rvhat is u-anted is patient sifting of better evidence, if such be available. Much of the material for this article has been taken from my Catalogue of the Triassic Cephalopoda in the British Museum, now in preparation, and I must expressmy grateful acknon'ledg- ments to the Keeper of the Geology Department, Dr W. D. Lang, not only for allowing me to make use of this unpublished information, but also for enabling me ,.',{Jessecau,,dllecluerlceur oq 'palcage lou ,(eur suorluJ5rpotu eql q8noqrle lou sI luarunS:e uleur s(JIo./y\ePuIqcS ler{} pu" olqerre^ .{1euer1xeare sqcuocolo,rdosei{l }Et{}}Itupe III^aclng dq uerrt8 suol} 'slleqs -Erlsnllr aq] qtr^\\sa:n8g leut8uo s.e]?od aredruocot{.{a esoq} }nfl pale8uola 'JeloeJotu 'toq]nu oql e{rl 'pe1cr:1suoJeq osle deur sr.uJoJauoclleJq eI{} }EI{}slcalqo rellzl egl ienbrlqo aq o] suIBIc ,\\ou clng qclq^aBlQod ,tq peqsrlqnd uorlcesuelPetu E '}ue}suoJ uorlerlsnlll sH roJ pesn Jlo.^Aepun{cg{laleuntroJun ssalro rrour Sututetu -eJ rll.laoJ8yo a13uearlt 'lecruoc sr Suruur8eq oq] seddl cIuoJIAeJqeq] uI seaJer{.{\ 'prolo Jo lecrrer{dseuocaq pue pue:addn eq} }€ lcer}uoc d1r-ressaJeu}snur raqueqc 'auoclSuol 'pele8uola 'sreqluet{c Ierlrur eql uJoJ ue ur lzrll peuleluletu eq puu Surpaaccnsoq];o adeqs eqr .{q peurrura}epeq feur qcuocolo.rdsnoererlec e qcns Jo 'surroJ eduqs arlt -\\oq pe,{aor{sJlo.Aaepulqcs uBIrIAoPrg (zr6l) s(uuetuapong pue 'O upruoleq :addl (669I ) s.e1-re13go asot{}uro{ poraglP qrlr{^AMnlDaop uEIuo^eO -osetrl ,(1pnbeslq Jo sl{cuoro}o;d pa.rn8goslu (}z6r) sua-r-ro3pue i (p-o t'8t.I) euo}s -aulT deqoqnlg ueruolaq e1ppltrNeql ruor; sotarorytlo Jo sqruoco}o-rdsnoererler 'petunsse aqt uo suorlelrasqo dq {ro,,rrs(e}rod perlridure,{1arr1 setl (296r) tt"$ 1a4aef 'a't'aasl se'paqce]le lou uJ\\ .ieqt tuqr t)BJ ai{} pesser}sosle oq.tt'(to6r) sau-ro11 '(Lo6r 'lo6r) 'sutatot1l.to ,(q passncsrpele.{\ ut.-ro.1.iq page-rlsuourap Jo qcuocolo.ld aql Jo ruroJ er{l ur sE IIo,Aase suorsueulp aql uI seJuereJtlPelqereplsuoJ aLIJ 'snqMDLp l0?1!.u?aqJ (t)
'seuuoururepapoc-,(llr{3r1 aq} uI ftrlrclel-re.Lssa1 .,{11ernleu sI oJerl} 's1-roq,ln '8ur1roJ tnq ro sJoqtueqcSurpeeccns eql 5o edeqs pue uI socue;eglPeq] uo ,srepro 'luepuadep 'oJuu1-todur qloq ur uauo sr ,{;uuud Jq se parePlsuocoual{}It{ ,ecue.regrp 'sprolrtntu sHI pue sprouourue ur raqur€tlc IEIlIul aq] go lueurdole^3P puB ruroJ ar{} ur acuora#rp iBr}uassaou se,{\ araq} 1eq1SurnltupB ,,tq ruelqo-rd aql 't}efH pegrldurrs ,{1}uacarseq (zt6r);1o.,r,r.epurqcg 3o ged eq} uo uolldurnsse ereur 's8rg) E se^\ (rg'uS leqruer{r }srg IBntJBer1} Surpacard'sptoltlneu uI qcuocolo.rd 'o8e 'ocuerg 'e1e1g snourlorqcuocE Jo eJuoJsrxeeql ]"q1 s.reedoS 5o ptre epuerreg 'pegrclec '.reppe1q suorle^rasqoeql uorJ pellnsar,(1.rea1c1r dpefqnopun lecrregds Jo '(zo6r) e;o (1-roq.rnSurpeeccns eqt uo) uorsse;dtureq] Uel qcuocolord eqr qcll^a ur 'rene11 1a4eef dq parn8g xapuo,ttoqsnlqno^[ cISSBITJenbrun ]eql o] ecue].rodurt '(t '3tg) qcnu r{r?}}E }ou plno.^A.I alI{AA snoererlec ere/!\ sonrollLto uEIuoAeG pue 'uercrrropJo uerJnlrs ureuac Jo sqcuocolord eql letll o8e sreed ,(ueru ul\oqs ueeq seq 'paqs '8tg) tl lo1 s.,te,rn1e.(peau sr pue snoer?rleclou sr (aS splolllneu aI{} uI qruoc -olo.rd eql teql (gtrd) palressedlploq sr y'ffio1oruoavpd ol uoq)npo.tlul s(seIAeG 'v 'JoJd 'acue}sul 's{ooq-}xe} de1.ro6 s? {.Io,{a-relndod B l{cns ut roC ulo{ Pallnc 's.rep.ro aq louuec ,(aql ro; o/yu or{} Jo uol}cur}slp eq} uI ecueuodrut Jo seJnteal eq} 'sproplneu Jeprsuocarol dresseceusr lr aql ol {JBq splouourue aq} Sutce;} aroJeg .YgCIO'IIJNVN ONV VSCIIONOIAII\IVNggAJgTI SNOIJJNIJSIC'II
'suorlcas A.ressecauJo spaJpunq aql Suuuderd uoq^\ a8-reqcs5{ ul suor}cellor palle^Irun oq} uodn .,(1ae-gos aErP o} rc, upo{olu7da3 ary {o uoltnloaaaL[J 422 L. F. Spern
tt lig. Initial chambers of Devonian Orthocerat ("-f) and Gyrocerotites compressusBeyrich sp. (g, lD. After Sulc (a-d, x r6), Clarke (e,f, xzS : " Bactrites"), and Branco (g, h, ;.;zz). Note the diffeience in the first suture-line. w ffi
Fig. z. Initial chambers of Ammonoidea. a, b, Acanthoclymenia nealsolitana (Clarke): protoconch, with external siphuncle and striation on part of first r,r'horl. c, d,-Anarcestes plebiifctinus (Hall): ';
(z) The coiling. The gradual coiling of the early Cephalopoda,followed by a converseuncoiling in the Ammonoidea has come to be regarded in palaeontology as one of the most firmly establishedcycles of development. There is no need to go into the history of this cycle, but I may recall that at first ( t867), Hyatt was rather vague about the Orthocera.sancestry and still considered all ammonites and goniatites to be derived from Clymenia, the latter being distinguished from the coiled nautiloid Trocholites (FiS.4c) merel) b).its more discoidalshape. The "logical picture" of the c1'cle rvas elaborated only in Hyatt's paper of 1883 and especially in his u-ell-knorvn Phylogeny of an Acquired Cltaracteristic Q8g4), and he there admitted that he had " deduced" the cycle of coiling or " morphic succession" from the individual development of the coiled shells. Hyatt, of course, was not unarvare of the rveak links in his chain of evidence, especially after the exact ages of the r-arious forms became known, and his papers contain many contradictory statementsand more or less doubtful admissions; but his followers made light of the difficulties. Over- looked rvas the fact that the first Devonian (or Uppermost Silurian) and the last Cretaceousammonoids are typically coiled shells, as was Hyatt's o\\'n reservation that Bactrites, the supposed straight ancestor, may after all be an uncoiled goniatite, 6z IIIA u a 'gS 'dd 'Surpuelsrepun : LS uo snoeuorra erour llrls peJepuer pus paleadar sr 1r lnq -slur snolJes dlJBIncrUEdB o1 onp eq lsnur luetualBls Jall€l eql (('seuocrlruour -tue 'seuoJourrur 'surro; 'se8zaurl Pelloc dlfq8rl pue pellec palroc .{1esoo1ere oreq} 'og 'splolrtrneu ,{uzru 3uo1e ur Suruncco l?q} o} Jelrrurs uorlnlole JaqunJ Sur;np Iloqs plouoruure eq] 3o Surpoc e roJ paredard ere e,1ylecrper prououue d;eurrrd 'ure8z 're,{I eql snql sr salLq?o{ ,, ipe}B}seq }}zdH 8ur.l,ro11o; ,.'a8eaull prolr}neNl 'd;erluoc '1nq'acuo ,irarreJoJ eJuanbasleurrou eql Suraq eql uo lnq paJJncco3ur,,r.eg '.(pearle'puv lou uollnlo^e slql -ro; pe-rederd,,sl eq (('euoJrlllneu o1 euocord8 pue euocolr.{c q8no;gr Sutpaecord pue ouocoglJo u? q}rllr Surge}s 'uor1n1o.taue sr ereq 'd1snor,rqo,, 'trozoeel€d : pepnlcuoc pue or{} o}ur {ceq snfruo^I8ur.r,rnrnsoq} pecer} '>lrlrC 'pre,rpoo1y\reg17'saurl-ernlns ('? or pacnpar IIV) pu€ prooC'rpruqcg'11 pue suortces-ssorc luaJeJIP Sur.noqs (so.tatot4so3o,n4'sayurottot4'sapuo7V ''s's say4otuog) elcunqdrs puralxa qlr,4l setrrl -eruo8 'laqtunC 'ueruo,req 'elcunqdrs snoreJluoqre3 3o sad.{1tnol'4-p rerye reddn l€uJelur e3-re1puu eEpa letdas aldrurs qlt-u'(:a1su)I,N) ololflas4sn7uo otuaut1co4trt3l>o 'sirrtuiuo8 pue ozuarutlC 'S '8tg
'(6r6r) .O .lA eq qcrq.{aur ,, selruourureJo uor}nlolg,, eW uo 3ue1 .,(qraded iloqs e ':eaa.tLog'lst8olo}uooeled uro{ uees eq detu egt dq pale:dro}ur se/rtsrq} IIe.&\oH 'r{}to; os pue 's-rolsaJuepelroc ruo{ Po^IraP ueeq e^Br{ 1{3nu PuB 1y\orrnJlesrop drelrporer{ e pe,{aoqssznrolnC3 ;-:zc:d,f,1 'outll oql lBI{} uI suol}?lor l€Ires qcns ou erad\ eJer{} }Bq} lno palurod p€q }}B^,(H 'ure8e 'atg) re.( ise8els (/S prolrlneu pelroo .,(1aso1caql puc ,(ag .Brg) crlrle:aco;,(B '(g '8tg) '(z '3rg) pelloc dlesool eql I rlllteroJolr,b peunc aql I rrlrlerecor{uo }qSrerts 'sproplneu aql uolsseJcnsuI peqcBoJe.{{ clozooBled oIIl uI leql paUeSSBse/K lr ol sV Szl upodolutlda3ary {o uolru1oaaaqJ 426 L. F. SpnrH " In all the main lineages of ammonoids, the shell, so far as the evidence qoes, passedfrom a bactriticone through a mimocone, to an ammoniticone." Hyatt, of course,never would haveclaimed anything like this sweepinggeneralisa- tion, and A. E. Trueman (tgzz, p. r+r) was careful to ascribethe omission of the hypothetical " straight " stageto " skipping," adding that in the Mesozoic ammonites "it could scarcely be said to be represented at a11." Unfortunately, the enormous increasein the number of Palaeozoicnautiloid genera alone from a few to manr' hundreds makes it impossible for the non-specialist to get a clear view of n'hat Hyatt really demonstrated, and what he is only assumed to claim, but the later expositionsclearly show how misleading Hyatt's cephalopod " cycles" have becomc to the general palaeontologist. But what must be insisted on is that Hyatt's cycle of coiling, put forward in the enthusiasm of the early evolutionary discoveries, was elaborated entirely on the basis of a fern'figures published by Barrande in 1865, but apparently not seen br- Hyatt till after the publication of his first paper in 1867. The individual chieflr' responsiblefor so much theorising was one of a number of young shells of Goniatites fecundus Barrande (1865, Pl. XI, fig. +, magnified five diameters) in which the microscopic initial stage is unusually straight. Let it be noticed at once that there are other examples, undoubtedly of the same species,without trace of a straight stage,some being open spirals, some closed.The illustrations are not incorrect; the speciesis fairly common, although the individuals are crushed and the matrix is unsuitable for section cutting. It is also necessaryto mention that the position anC character of the siphuncle of the earliest goniatites are not known, and differences in coiling, in any case, were not considered by Barrande to affect the specific identity of the minute individuals, rvhich, at anv rate, are absolutely indistinguish- able at larger diameters. Hyatt in copying Barrande's figures also included them under the one name Agoniatites fecundu.s,but why he did not apply his recapitula- torial reasoning to the concentrically coiled individual with spherical protoconch (Barrande'. fig. z), which did not fit into the cycle of coiling, was never explained. These trvo extreme forms as well as all the intermediate types came from the same bed, and there is no more evidence for assuming one to be a less primitive or later type than there is in the case of, for example, the Cretaceous Scaphites c'ircularis (from bed X in the Upper Gault), discussed below. The innermost whorls of Gyroceratites gracilis (: " Mimocerts" compressum)are equally variable, which is important to note since a largely magnified and wrong drawing of the beginning of this goniatite has been so widely copied without mention of Branco's own correction. Yet the configuration of the earliestwhorls is still consideredto be of importance in the distinction of members of the two orders Ammonoidea and Nautiloidea. Thus Schindewolf stated that the beginning of the shell in the Ammonoidea was always the most conservativeelement and rvas the latest to be affected by the subsequent modifications of the shell, and then not until a very late stage. But the very opposite might be claimed when uncoiling sets in. Of course, it is true that some hetero- morph, i.e. uncoiled, derivativesof normal ammonites possessthe spiral, transverselv elliptical, protoconch of their ancestorsand may retain one or even more complete z-62
,,1q8re.r1s,,e,&\oqs o1 suaddeq reqr'snpunta{ saq4nruoty'>ico1srrrau .,(lerrnemd -uroc e Jo Ienpl^lpul e18urse alrq.^aperou8r eq plnoqs a8eaurlprle;acoldl luerruz ue qcns ur 3uno.,(eI{} Jo Sutpocun elr}BlJosuocun }sour pue olqe}sun srql dqrvl uosee: 'ur-roJ ou eq ol eul ol stuaes erer{} 1nq slt{} uI punoJ uoeq trou sBr{ 'dleleungoJun 'qcuocolord 'spllltuer{ 'lI" aql pelelJosseeuros ur sB l" Surqcnol dlecrecsslenprlrp -uI Jer{}ouI Jo re}eruelp seJ}eruIIIIu ,e\eJe 1e f,peetle seur}ouros }ce}uoJ olur Sururoc 'Suruur8eq '(ft 'St.E) slroq/K ar{} qtl,!\ elq?}sun dlaure.r}xe uB s./y\oqsf1 fed suorl -Isuerl Jo selres 1ce;;ed tsotu eqr ,(q uEIqlV lsou.reddn oql;o (dno;8 snuntp.to7ntl) saqlqdocg .req8rq txau eql qlr^\ pelceuuor sl 1I '(sa4q,07doanp4) serrJ re.{toT
('t x :luur8r-ro sraqto 1uo11rg ur 'dqra,rog :efge p) 'uorluroy-red 'sarlar.re.1. 'auolsaqlog ,auoz I€cIIIqurn e3.re1qll,Lr, a elnlole pue elnlolur seurpno '(d_q.re,,nog Jo tunsorttoo'l1neg .ladd11 'l ep 'I) sxtolnz,nrsa7TqQocg't-p (uetcr opro g'uelcopeuara 'uuetuepang '{ 'elcunqdrs 'ued11 'c 'alcungdrs 2 PtlE D JaUV) x 1es-ropqlr.a,r ?l?o?f)n sola?olxlotl?o.ta i x 'uuutuepanll 'q 'uorlelo;-rad { IeJluelqns qlr.u uutlotaruDJxqnruso.tattqd,LoJ i ! x lecrlqun ll€rus qlr.r\ '(plegtltl$) 'ueprouotutuv '] 'SIg z[a1aassont(,qdna'z pue €aprolr]n€N ur suorle.ro;rad lucrlrgtull 8e8
'ssal.Lleg 'sarn1ea; eql 01 {ceq sr ee:8rpad stl l?q} os }soru ur so"rarolfT xopoqUo 'dq.re,tros 'C u? lsotrrl€ sr (uo11rgur op 'I) sxtolwn? saXtqdocgsnoeoetarJ eql dlarueu 'urrou>1 'pa^rasqo sa\n1docglsellree oql sr dlrluepr cgrcads lca;red ]Er{} tlnpu ar{} ur ,t1uosr '1e.rrds l1 ploclleq E uI ro aueld e ur'r(11e-rlsrursro d11e:1xepIroc deru 11eqsaqr 'paqcslep 'esec 'sonto'tt{g pue pue lecr-laqdssI l{Juocolord eql ,{ue ur crssernf eql uJ 'csnllotu ;o ed,ft raqloue olut e8ueqc ecuo fe IIB lou saop elruotuure uE ler{l ueq} '(?'qS '8tg) erour ueeur lou seoPslgl lng lerrds teln8ar oqf go Suro8 eroJoqslror{./v\ Lzl upodoluqda3ary {o uo1ru1oaaarlJ 428 L. F. Spern beginning should have been selected by Hyatt from among its less elliptical and more closely coiled associatesin support of a risky speculation. If there are no essentialdifferences in the form and.development of the initial chamber between the nautiloids and the ammonoids, surely the mode of coiling of the next rvhorl or more is of still less significanceand equally adaptive. Of course,the mode of coiling by itself in the young or adult has long since been given up as useless for indicating genetic affinity. Zitte\, while recognising the weakness of Hyatt's classification, admitted already in r884 that in discarding evolution or coiling as the chief characteristic,it was lkely to give a truer picture of the genetic interrelations than previous classifications. But, as regards the Nauti- loidea, Hyatt was again most contradictory. In r894 (p. 168) he assertedthat " all except the most primitive series,which were composed wholly of straight or arcuate forms, had some close-coiledspecies. These we could often trace directly with the greatest exactnessboth by their development and by the gradations of the adult forms, to corresponding speciesamong the straight shells." Of course, it can easily be shown that the " most primitive series" were of Hyatt's own construction; even Lituites had then been recorded from the earliest (Ozarkian) strata. For his later series Hyatt relied upon such Carboniferous cyrtocones and gyrocones as were copied by him from illustrations chiefly by de Koninck. Nevertheless he not only failed to show why development must have been from straight to coiled, but also pointed out that the earliestnepionic substagesdid not have equal circular bands of growth even in true Orthocera.r,and are never quite symmetrical on dorsum and venter. In other words the descriptive term " straight " is only applicable to the apical cone in a general way. It is the " straightness" of, say, half an egg-shell, transverselybut obliquely bisected,which is the shape of Ray Lankester's (r883, p. 66+, Fig. ZS) primitive siphonopod (Fig. nj), or of Verrill's (r896, p. 99) mol- luscan " archetype "; also of primitive Clarkoceras and Piloceras, and of the apical conch of many coiled nautiloids. Let us examine, however, whether development need be from a straight to a coiled stage. For example, the three Devonian genera Ptyssoceras(cyrtocone), Ptenocera.s(gyrocone), and AnomalocerAsr(nautilicone) were united by Hyatt in his family Hercoceratidae, and we may agree that they are closely related. There can be no doubt, hou'ever, that they represent merely a morphic succession,shou'ing an increaseof coiling, and not a filiation ; for Ptenocerashas its own cyrtocones,and the straightened outer whorl of Hercoceras suggeststhat in the same stock Ptyssoceras- like cyrtocones were also produced. The last (Anomaloceras)is more globose but vvith umbilical perforation and it is close to Halloceras and Kophinoceras; and the forms of the latter, with large and rayed ventral siphuncle, lead directly to the true Cyrtoceras (: CranocerasHyatt). Hyatt himself admitted that Cyrtoceras " mav be degenerateand have arisen from coiled forms," and that the next stage in the un- coiling is presented by Joztellania.Anyone who has examined specimens of Joz:el-
L -Jrronaloceras Hyatt, 1883, is not taken to be preoccupied (by Anomalocera Miiller, 1837 [r8:8?], or ,'lnornaloceraWestwood, r84z) as Cossmann (Reuue Critique, rgoo, p.43) held; anci Hyatticeras Cossmann (non Hyattoceres Gemmellaro, r888) is a synonym of Anomaloccrns. '(S65 'd) Jo raqurnu E elrnb are oraql dlrleer u1 ,, parruep ueeq e^Bg plnoc tr qcrq^\ tuo{ urroJ pelror Surlsrxa-erd.(ue,,pug o} sB/Kft1ncgrp,(po srg'-rolsecuepalroc '{S '8tg) 'pedegs-deupg 'a't'crlru4deu ? uro{ pe^rrep @ aurltrno pue ^\orrnJ IBSrop slr pue ,,'e1eJouo3rp,,aq deu (*sontouoe,,:) soncoutJ leqt Surtlnupe ueql\ 'peapul i(Sqt'd) pe1e1s}]BdH sB((Baprolflnug or{} Jo elcrper,,? eg }r uec.^aoqos 'urnsrop '.r\orrnJ aql uo ?uoz pesserdurl s5{} seq sonro4nC3 wg IBSrop,fue1rpe;eq .ro '(}69r) ((errozpesse-ldul or{1,, sllec eq ler{^ag}lie peurecuocdlureru sr ,. crlsrra}cerer{c pa-unbceuB Jo,(ua8o1dqd,, egl's;eded tuelrodurl lsoru s,trledHJo euo'rnoN
('ztx t lStx tl 'i 'pecnpa.r '969r '*loH 'vueutepeng lnoqe x pa8relua a 3'{'p-o i11u11raf;e 3 f JeUe a'tz6r JeUe q 'ollocl JeEe x 'q 'p 'c 'o) 'saplnJDg e ur a8els erues '? 'uorlces ut ,sontopquely 'prououruru '? '(tteH) lq8re-r1se go Suruur8ag pelroc runuz??nqsonnntqflalll'ea.rz les.rop (a,rucuoc) pesserdrur qlr.tr suoJllllnsu peluuur 'E '{ 'prcnur 8ur.toru alcunqdrs 8ul,u,oqs '-IoH ossuuap 'tvt snalo.tdso,t;,zotuolsg 'pro1r1neu,{1.rea 'a8e1s 'sagtnyta -repurs B Jo xedy'a lgElerls Je}€l E yo gud pus palroo d1:ea ue Sur.Lroqs 'p 'llaqs pelroc -,{1asoo1'a't 'auoJotf,{) 'c 'sEuulreu Jnolo3 q}r.u '1yaqs peAJnJ 'a't 'euotogJfJ 'q '11eqs (auocogug 'rz 'uaprouoruuv 'S 'EIg lg8rerls'a'x pu€ BaproplnuN ur Sullroc go sadfi lueJegr6l
'uortBldes asolr .,{1-rerlncadpue 'elcunqdrs urroJlullce pefeJ ,(11enbauB l{}r,ll' pue palrocun dprepuoras sa^lasuoq} 'sn.tatottg 'd.repuoces pve sonro\,tt3 Jo sruroJ (ueruoneq d1-relnurs)eql ot dlrealc sr 's11egs sseulq8reJls esoq/!\ aseql Jo ocuBlquresoreqf [q {cnr}s ueeq eABq}snur olunl 6zl DpodopqdaSaqt {o uoptrloaaaUJ 430 L. F. Spern Lower and Middle Devonian generathat are closely allied and have a similar rayec, ventral to subventral, siphuncle, e.g. IYaedyceras,I{otltoceras, Kophinoceres,Anoma- loceras,IYephriticeras, etc.; and on p. Szo(r8g+) Hyatt himself stated that Cyrtoceras (: " Cranocera.r") appeared to be allied to the more closely coiled nautilian forms of l{aedyceras. So that if Hyatt's "acquired characteristic" has demonstrated any genetic successionincluding both orthocones and nautiloid forms, it is this uncoiling Devonian series going from nautilian to straight. However, there are comparable series not only in the Devonian, but throughout the Palaeozoic, from the Ordovician Lituitidae to the Carboniferous Trigonoceratidae. If, then, we remember that the larval stage was a curved cone, and that, as in all tubular or- ganisms, the shell grew by adding to the mouth, being thus free to continue in any direction, it must be admitted that it is unsafe to assumethat the successionfrom orthocone to nautilicone is " the normal sequencefor every nautiloid lineage." In fact, since only such series as go in the opposite direction can be established,we might almost go to the other extreme and say that secondaryuncoiling accounts for the occurrence of those straight forms (at least in post-Ordovician times), that by peculiarities of shape, ornament, etc., were linked with nautilicones. In a word, like any other single character, it is inadvisable to take the coiling by itself as a r,vorkingrule for all occasions;and looking at the evidencewith an unbiassedeye, it seemsto point to a cyrtocone as the primary ancestor of both the straight and the coiled forms among the Nautiloidea.
(:) The siphuncle. The position of the siphuncle in nautiloids even in individuals, is very variable (Fig. 6). Barrande stated as early as r855 (p. r6o) that it u'as precisely on account of the invariable position of the siphuncle that he excluded Clymenia and Goniatites from the family Nautilidae, in which that element seemedto be essentiallyvariable in form as well as in position. Branco (t8Zg) later showed that this dilTerencewas confined to more advanced stages and that in ammonoids, at a minute size, the position of the siphuncle may also vary very considerably, but he was very careful not to attach too much significance to this variability. ZitteI and Pompeckj also saw in this wandering siphuncle merely an indication of nautiloid ancestry. Now, however, Schindewolf (r93 r) put the position of the siphuncle in the forefront of all the characters of the young ammonoid shell, and attempted to show that most ammonites, including all the Jurassic and Cretaceousforms, must be derived from Clytnenia, the goniatite stock having become extinct in the Triassic. He based this sr,veepinggeneralisation on what he considered the phylogenetic process of the gradual displacement of the originally dorsal siphuncle (in Ctymenia) to an in- creasingly more ventral position, until finally the original condition was entirely skipped in ontogeny. This, of course, would indeed be an ideal example of accelera- tion, but it is not borne out by the facts. To show the " extraordinary regularity " of the displacement of the siphuncle, Schindervolfjumped from the Lower Permian (Agathiceras)to the Upper Triassic (Tropites, Trachyceras, or Sirenites) and then settled the host of the later Mes ozoic 'lqrryq 'urnldes erour tng s0,raronpo,t?rwrerlree eql ur sB qug-.{}ue.^{\}PuB q}3llue.^al eql uee.^AleqlBuretrxe auroceq few alcunqdrs oql sErT ra,{\oT er{} ruo{ Dtsorxu?ld sotaJonuaord u\ 'aldruexe ro; lqcnu dren o1 urees lou seop sarcads oures aql uI elcungdrs arll Jo uorlrsod eql suoD?Arosqodtu ot Sutproccz lerl] ecuo te des ,(eru 1 'slroq.^a rtz nrye dpea.rle ';lasurrq 'sagtuang Ieurelxa aru?Jeqlr Jlo/(epurqcs ol Surp;occe crsserrJ er{l ur uol{.lt '(s1-roq.la. 'uu eerr{t q}l^a) t[.t Jo retaru?1paqt ]e uale IBr]ueAeq tou ppor{s elcunqdrs eqt sxsuauo7anDaqroquaol,/rs snoocelerJ elBI er{} ur dqm eas ol }lnoglp sr 1r q8noqt 'ursrlele dq peurzldxe aq dlqrssod rq8rur 'Suruur8aq eq] uror; re}uel er{l o} esolc sr }r sonrofsd crsserT ro.^aoTeI{} ur ueq.{a'(o L 'fu9) sonto&t.4s clssernf ttpptru e uI ro '.{lasraluoC sonto{,tog crsserT.reddq uE ur erur}euros JoJ IESrop Sureq elcunqdrs eq} ioruautrC13uer{} reqler saplotuog lurory e.reue8 eseql Jo uor}Blr-rap Surleclpul Jo 'sdeqred 'srqt 'sa\q1&1dopnas4 peelsur ,,'uor1zra1aJJe,,iercads ol peqrrow eq p1no3 '1no snoacele:J elel d;erl e ro sotaio.ta$V J$serl Je,{aoT? se lcurlsrp sB ereue8 ut '(saq7{otg '1e.r1uel -q8no.rql eprs I€urelxe er{l qrpe }ce}uoc ur Surureruer }nq ur uele
.pcrd^{1€aurpno ,c .tatt\z.,"rr",o(X,",iil$) 3ff-:}fj:J'i,1lt?#iirt*'fiiilm ro r'uorlces '3rg {:il:i? :addq ue'(1addg) octuocuo{ ossolSoc,og'q ('aS Jo r{cuocolord pa1cl.r1suooun.,(lreyrurlsaql 'aryu13 'uorlcas 'srequr€qc ur alcunqdrs 3o SuruulSeq ereduo3) :e13e pa8relua dlluerg eeJql lsrg uI 'plptnuu 'g'3rg elcunqdrs.reln8ar-rr8ur,r,r.ogs snoeculerC raddg uy'(uouotr4) {o4ap soncoqda,?ng'o
ssel Jo eJour sr{el|1esr Suruur8eq srq} suor}B^Jasqo,{ruo1 Surp.rocce-ro;) urnca?J or{} 'a't'Suruur8aq 'uot}rsod se^€el 1r aJal{./r{. eqf 1e dluo lou lerluen dlalrugop e uI e9 ol 'aprs elcunqdrs eql pere^ocsrpI rng leuralxe eql o1reryeuoos d.rene.roru o1 uorlrsod 'uorllsod IBJluoJssel Jo eJourE ur acuo 1eueSeq (( ses€c;o .,fiuofeur er{} ur,, }nq IBSJop (selruourure B ur oleur8rro lou p1p elcunqdrs eql snoerztarC or{} ur dylercadsapue '1e91pol€ls 'peruz^pe crsse;nf eql ur Jlo,/y\epurqcssnql oq plnor peldope aror{asoq} 'lptap uEI{t suolleuzldxa Jeqlo esecur ourosur ecueprla eq} UISo} d;usseceusr 11 'elrleluesarda.run d-rezrse.tr. IBrJelBru srq ssalun suorsnlc -uoc Surqraar-ra! eseql u/(Brp a^eq plnoc Jlo^\epurqcs .4or{ oes o} elqeun e}rnb 'elqectlcerd tue I uaae Jo IBJnleu Jerllro oq Jalou uec Jelcureqc a18urs€ uo pos€q uoTIBJSISSBIc€ wgt trEJ aI{} tuo{ gedy 'Suruur8ag eqr ruo{ uor}rsod elerperure}ur ue pBI{ elcunqdrs oql }€t{1 }ueure}B}s }ceJJocur 1nq Surdee^.s eq1 q}r^\ se}ruourure rtl npo{o1ot1{a3aqt {o uoltnloaaaqJ +32 L. F. SperH often it does not do so until about the fortieth septum. On the other hand, in the Yorkshire Psiloceraserugatum (Phillips) it is almost exactly the same as in the Alpine P. calliphyllum (Neumayr), being always close to the venter though not becoming quite external until about the twenty-seventh septum. Again it may be granted that Psilocerasalready represents an accelerated t-ype, since in the much later Phylloceras heterophyllum the siphuncle, central at first, does not become external until after the fiftieth septum. But a first difficulty arises rvhen such stocks as Schlotheimia and the Ammonitidae are examined, both considered by Schindewolf (and by everybody else) as derived from Psiloceratidae. For in Schlotheimia (Scamnoceras)angulata the siphuncle does not become external until about the fifty-sixth septum, and in the still later S. (Charmassiceras)posttaurina (Wiihner) the siphuncle remains central to the forty-fifth septum and is still rvell away from the venter at the sixtieth septum, the last visible in my section. On the other hand, in the arietid derivatives of Psilocerq,s,the siphuncle may be at first *,ell away from the venter (Arnioceras nigrumand Arnioceratoides krideon) or it may be absolutely ventral throughout (Asteroceras and Oxynoticeras); it may move slightly away from the venter only between the third and eighth septum in one Cymbites or be absolutely external from the start in another, while a third Cymbites *uy shoru u . subventral siphuncle still on the third whorl. It seemed possible that a ventral groove or keel might, at least partly, account for this difference, but I could get no confirmatory evidence. Foi in draspedites subditus (Trautschold) from the uppermost Jurassic, for example, the sipiluncle moved more quickly to the venter than in its presumable derivative, the keeled Garniericerascatenulatum Trautschold sp. (fiftieth septum). In the carinate Haueri- cerasgardeni (Bailey) again, as in early desmoceratids like Puzosia and.Beudanti- ceraswith equally thick siphuncle, it is central at first, before it moves to the venter at or after the twenty-fourth septum, but in the unkeeled Varunaitesvaruaa (Forbes) the thin and slender siphuncle is absolutely external from the start. The very mas- sive siphuncle of Pseudohaploceras(Deshayesites?) aburense again may be external already at the eighteenth septum, whereas in the later Acantioplites (nolarti -ofgroup) it does not move to the venter until the thirty-fifth septum. The vagaries the young siphuncle in the Jurassic and Cretaceousforms thus cannot be connected with whorl shape or ornamentation, and in any case, two examples of youlg Lissoceras(oolithicum group) from the Inferior Oolite, indistinguishable exteinallv, have siphuncles that become ventral early (eighteenth) or late (not yet external at the last, sixty-third septum) (Fig. 7c). But the Triassic forms are more important from the systematic point of vierv, for if (as we all hold) Phylloceras is the root form of all latei ammonites, its Triassic forerunners should be nearer the supposed Clymenid root stock. Unfortunately, here again, we find the evidence most contradictory. Thus in Diphyilitlu urri ^ Timor form of Leiophyllites (Fig. 7 d) the siphuncle is external at first, and while in the former genus it moves away from the venter only very slightly (and temporarily) to become external again after the twentieth septum, in the latier genus it is well away from the venter-at the fourth and still more so at the fourteenth septum (rj 'wnssrutap '1-rogrvr sn.tanqdgtpelllB dlesolc eql ur e1q^e puocas ro tsr5 ar{t uo ro}uel 'suruur8eq oqt ruor; ,te,u.u.(1r-re-rodura} pelour Lr sreqlo ur aqf tuo{ Ieura}xe ,(1fcey -rad 'puelueaJo ',rotttr.u.C aq .{eur aycungdrs eqt tseg Jo serrtr ro,,t.oT er{} uro{ Jo 'acuelsur 'elcunqdrs dno.r8 er{} Jo sonctqdoldQC euros uI elrq/y\ -rog eq} yo uorlrsod 'paururexe eql uI saue8erroql JoJ lunocce o1 llnJSIp eJour IIIIs sr 1r BJeuoBcrsser.rl 'runldas ra/v\oT er{} uI qlxrs-d}xls aq} }B Je}ual ar{} uro{ f,enteIIIIs sr elcunqd
'gzx 'sraqur'qcaerr{t }srg ul alcunqdrs 'rourrJ'serraeppltr\l .(scr.r.osrsfo1trl) 'ozx '1es.r-oq'allloo l,uretxg -16t7do7a7'p roIJeJuI'(.,(u8rqrg,p)runu4tqoo 'JJ sonlosslT,c .olx ,eruiogrluj 'serr; 'scr.ros1sfoy11'sn1pnbrc| .gzx ,1eure1ur "J;ti"#:'ifl ;ad{q sa|4{ota'q }srg lE elcunqdrg .lasJoCI ,"ijf"[ '(d.u8rg.rg,p) 'elselruoruure .L-,€r.j JoIraJuI npan4 sonco&utlg Jo slJog.rr.Jeuur Jo suorlcas uerpe141
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'r4lr -rs eql rypwo,tol (sa7111'Q7dop7) crsserrJ elppl6 drerodureluor er{} ur ep{^a 'elcunqdrs 'a8e}s leuralxa dlluelsuoJ B s?q sn11'Cq{onoqdssaqptQldouo7y .,{pea uu 'selcunqdls 'ure8e 'saptoasfo74y ,sa1tgrfi1d }e lwel 1e sde,,vr1e]ou JI leuJelxa aABq pue -oaolod 'sa\qltqdocstq 'r{gg-fgo; oqt raUB erour ecuo leuro}xo auroroq o1 (s1:oq.,rn, tt, upodoluUda3aqt {o uognloaaaqJ 434 L. F. SperH from the same bed, the siphuncle may be definitely away from the venter, i.e. ventro-central to a diameter of 2'5 mm. In the more discoidal Lytophiceras the siphuncle is external or almost external atallstages,also in " Meekocriorl, (: priono- lobus) and Proptychites. I am not laying stress on the fact that in the Lower Triassic Anasibirites multi- formis Welter, ihe siphuncle is almost external on the second whorl and that in Columbitesparisianus Hyatt and Smith, and the Mesotriassic Tropigastrites (,, Cel- tites") aff. neumayri (Mojsisovics) it is also external already at a viry early stage, becausethe connection of both Sibiritidae and Celtitidae with the Tiopitida. -"uy be questioned. It is well known that in the Upper Triassic Tropites (FiS. 7b), the siphuncle, internal at first, may not move out to the venter for a very io"! ti-e (3rr- whorls), but I have found considerable variation even between Tropitis urd i[. compressed Discotropites. Now Tropites has always been held to be derived from the Carboniferous Glyphioceratidae, though probably wrongly; but in these goniatites, in any case, the siphuncle may be either well away from the venter or else as close a, Grundj.urt (t9r r) has drawn it for Gastrioceras.In the glyphioceratids from the Coal Measures the siphuncle, with the sheath continuous, often is of a rich golden brown colour in a clear matrix, and there is even possibility of confusion with the Liassic promicro- cerasplanicosta, if the labels were removed; but in the Lower Triassic Ophiceratidae and the Devonian Timanites the preservation may be equally good. Unstable siphuncles had long been figured in Glyphioceras, and were known to occur in Dimorphoceras,Reticuloceras, Homoceras, and other Carboniferous genera. I suggestedin r9r9 that Clymenidae were derived from a goniatile ancestorwith a siphuncle the position of which may have been unstable as in the early whorls of most latisellateammonoids. I have no reasonfor distrusting Branco's researcheson Clymenia, but in any case, Clarke had shown in 1899, lh"t the earliest known Clymenia also had a ventral siphuncle at the start (Fig . za) which moved to the dorsum only during the first whorl. Nevertheless Schindewolf declared categorically that there was never any shifting of the siphuncle in the goniatites and that " types with the unstable position of the siphuncle, postulated by L. F. Spath, withlut doubt did not exist." Unfortunately most Devonian goniatites are preserved in crystalline calcite, if not pyritised, and do not show the siphonal sheath as do those from the Coal Measures and other beds mentioned above. Those Anarceste.rand Agoniatites from the Lorver l\fesodevonian of Hlubodep (Bohemia) that are easily secttned, show an external siphuncle from the start, as do Tornoceras,Cheiloceras, Manticoceras, and Timanites; but the (anarcestid?) ancestors of Acanthoclymenia,with presumably unstable siphuncle' are as yet unknown, and the Lower Devonian Agoiiatites, etc., ate far too rare and too poorly preserved to allow of investigation of their internal features. From the recapitulatorial point of view alone, I must doubt the existence of that hypothetical (Lower Carboniferous) " passage-form" between the Upper Devonian Clymenia and the Permian Agathiceias, stlpulated by Schindewori fut in the Middle Carboniferous Glyphioceratidae and Gastrioceratiiae, in any case,the 'd'9z6r'uosspaoll) (zz peurelureuruaaq uelo serl 1l 'elcunqdrs xelduoc pu€ e3.ru1 'sptolllneu '(suorlcerrp qlt.trr Jo as?c eql uI lecrgel-uou ur luaruerrou Surururt,&\s 'esJnoc 'uotleulpJo-oc I{Ura 3o ur) >1ursJo esrJ o} lueur}snfpe lselqEqs eqf perrnber ,,{po 1r leq} re}E,l\ eas Surpunorrns ar{} Jo l?ql ol Jeeu os se.A.t.}ue}rqer{ul s}r pue lloqs 'slassa^-poolg eI{} Jo dlr,rer8 cgrcads oq} purur ,(ur ot 1nq str pue elcunqdrs er{} Jo PIB or{} qfrm dl4clnb 1ou 1nq ,(yrrols peleln8er ueeq o^Br{ }q8rur (selruourure }cur}xe aqf dlqeqo.rd e.ro;e.reqfpue) sryqnol{ Jo srequer{c aq} ur se8 Jo ernsse:d aql leqt '1q'oz6r 'Baprol pe1se88nssuq (926r) rpruqcg ur uorlsonb srqr pessncsrpJ acurs -frnz5i aqt uI uer{} Boplouourruv aq} ur }uzcgru8rs a.rourag ol ue>le}eq uec uor}rsod olqEIrEA sll Jol{}eql\ o} se pue alcunqdrs er{} Jo uor}cunJ orl} ol se .(rrnbur rno ur 'sproplnBu 'se8pa o,\A.leql lcauuoJ otrsnorlqo suroes1r ur se 1e1deselduns qlllA peulq -uroo sI elcunqdrs .(1-reeolq?Ire^ pue alrsseru oql sB pue l1-roq.,rrler{l Jo r{}plrw arl} Jo r{lalull{}-auo o} prlq}-euo uro{ ,,(lleuorseccoSursee.rcep 'se3?ls Je}?l oqtrqlra pe-red -uroJ 'BAJel sB glpl.^aleor8 Jo ueryo sr elcunqdrs eql slror{,/y\Jarlree eql uo }nfl cruo} -1uu1d 'a'c'e?egs B sE UIrp ol pe$eJ lI ueq.l.r' r{ruocolord eql Uel IBurruBprouourue er{} reUB aJII Jo eporu ur e8ueqc B e}elnlsod oq,r sre}rr,^aosoq} qtr.tt eer8e 1 'asuauo$?qrryoqsonropuJ ur (9o6r) 8ur1teolq 'seqnl 'acuelsrp .(q pecnou se relncunqdrs procrlaq Jo ses?c dlqeqo-rd B roJ lsol sr ,(lleuorsecJoalcunqdrs aql suollJos u€rpeur .(ltceyred ur uele se SursrrdJns eJour 'e8els '1.rog,u. aql IIB sl sHI IB^rBI oI{} ur un8aq e^eq }snur .{;}aururdse trsourreuur eql ol suotltsod Surpuodserroc ur elcunqdrs 1eu.ra1xeeql s,^aor{suor}ces eq} w pue 1'urur oz ot or uea/v\leqJosreleurerp lE eprs ouo 01 peceldslp eqol Ieuoqdrs aqr peq '3'a 'se111eruo8 u/v\op punor8 I sz.raJouroJuEIuoAaO eql Jo auo ur /vrou>losle sr drleur -ru.(sy 'peorlou 'uorleldas 'lueuraculdsrp uoryo ur ,firpqerre,r.lear8 ar{l Jo lecrlrerr 'rfirpqelsul oql elrl lenpl^rpul ot enp aq dzu elcunqdrs ar{} Jo tueueceldsrp 1e-re1e1 (lloqs ar4l'so,tacofsdeTI pereluel-punor E ur lnq la;r1 ruolloq qlr^\ palcouuoc oq 'lue1suoc 'sonc4ua7Qold '11aqs 'a.t 11arr,(eur 11 sr .,fu1eurur,(steroq,{a a4q o}nce [ta,t 'laa1 'eldruexe 'a1ou,(xoue uI B .ro3l';o luarudolelop oql qlr.l. -readdesrp,(eu '8unod 'lo eqtrur punoJ ual{llr sa8els rlnpe eql sesrJelceJer{cueryo ,iren ,{.rleruudse seeJer{,{\ 'ezrs elnulu B otr peusuoc sr Jellel eqt uortdocxa lnoqlrl\ roJ 's1;oq,tnr(1-lea oql ur uorlrsod elqelsun eq] uer{t serueregrp le}ueuepunJ }cegar o1 ,{1a>1qerour uole sr elcunqdrs eq] Jo ,fu}eunu.,{sele.{'ecuelrodurr cr}Burelsds;o pereprsuooJaleu g8noqrle 'oJII puv Jo eporu tuaragrp E ol uorlqdepe 01 ro .,$rpqelsurleuorlnl4suoc ot anp se^\ qcgnt lnq dcuelsuoc Jo aar8ap elgeraprsuocE urell? deur lrqt dlrleurrouqe uE .,(lereru su palerdJalur ueeq osle ser{ puz se}ruourure ur q8nouo uoururoc sr 'dr1eruru.,{seo1 'aue1d 'eeprouounuv Surpeol slq] uro:; f,enteuorlcoJrp B ur lueureloru }ng Jo uorlecg 'Surpoc;o -rssulc^\eu e Jo srs?qeql ep€tu uoeq seq srgl asnecoq eueld eql ur ]uetu -elour sp.re8a;sB olcunqdrs egt yo dlryqelsur eq] dluo paraprsuoc a^Eq a,l '.re; og 'pleqdn eq louuec s1y\orls(Jlo.^aepun{rs }Er{} 'r{poqdJale errr ol sureeslr ol lue:edde eq lsnur saplotuoC uro{ ouros pue oruautt13 'sonton4strz uro{ spr}auz euros Surnr-rapJo ,qlllqlssodurr eql ecurs pue crsserT reaoT rBIrruIS aql ruo{ sr rel}El er{} sB (elcunqdrs leuJe}xa ,(1}uaueu-red qq^a) sa417&7dn&a6usser:a -reddg oql ruo{ orur} ur peloruer rBJ sE }seel }B are asaq} ecurs 'eeprleroJlqdo cISSETTJre,^AoT eql ur se elqelsun sEeq ol u^\ou{ sr elcungdrs stn upodopq{a3 aqt {o uo!&loaa aqJ $6 L. F. Spers
that it helped to increase the gas-secreting surface, and thus served the same purpose as the folded mantle-edge of the ammonite animal. There is no need to go in detail into the many siphuncular structures found in nautiloids, but it is well known that in the (polyphyletic) actinosiphonates, organic deposits in the form of " obstruction rings " were formed in the siphuncle, while the inconvenience of too great a buoyancy was counteracted in the endoceratids by loading the siphuncle with funnels or tabulae. The endoceratids in which this loaded siphuncle was marginal are often found facing downwards, as might be expected in presumably horizontally disposed swimmers; but in Protocycloceias the comparatively enormous siphuncle was more central and in the Lower and Middle Ordovician there are transitions not only to more typical orthoceratid forms such as Bactroceras,with a slender siphuncle in a marginal position, but also to the (episto- matous, i.e. upright) forms with central beaded siphuncles. In Orthoceraittisand even coiled forms (" Discoceras") again, too great buoyancy was averted by casting off the superfluous air chambers, altogether or in part, and sealing up thl broken end (Barrande, Frech). Beaded siphuncles were also produced over and over again. For example, the gigantic Carboniferous forms are certainly not descendants of either the Ordovician stock, or of the numerous Silurian adaptations known, with constricted mouth borders and similarly differentiated, central or marginal siphuncles. Again, in a form like the Silurian (Clinton) Orthoceraserraticun-Foerste (t893, p. iS6) there was not only constant variability in the position of the siphuncle in the same in- dividual, but the earlier annulate structure became cylindrical in the later-formed part of the shell. In the ascoceratidsthe reverse change from orthochoanitic to cyrtochoanitic was probably due to a more abrupt change in the mode of life, but equally devoid of palingenetic significance. The slender siphuncle rvas purely adaptive and appeared more or less independently in the .truight, swimming, crawling, or mud-burrowing forms as well as in the brevicones which lived in ro& crevices, or in the forms with nautilian curvature. As I have already stated (rgzo, p. r43), the assumption of gas secretion by the vascular siphuncle is not supported by the many fossil nautili in which it is separated from the cameraeby thick mineral deposits. On the other hand, it is almost certain that the typically regular septation of Cephalopoda as a whole and the formation of chambers filled with gas (as distinct from tabulation in other tubular organisms) is dependent on a posteriorly attached siphuncle; for it is clearly of as much functional importance in the recent Nautilu.r as it was in a homoeo-orphorrs Silurian shell, or in the latest Cretaceous ammonite (Indoceras, with.o.rrtu.r1ly external siphuncle) as much as in a similar Devonian goniatite. And yet, it may be cut in ltautiiu.r, with- out affecting its agility in the water (Willey). But my suggestion that the pull exerted by the siphuncle accountsfor the progression of the end of the protoconch (gradually decreasingin size on the whole) from asellateto latisellate and angusti- sellate (trig. z) is not necessarily invalidated by the fact that in an Ordovician IVautilus(lituitid) the caecum may resemblethat Lf an ammonoid (Fig . 5e),whereas in the recent l{autilus the siphuncle begins at the posterior end of the first chamber '8t_f) ,puug dlrruurp:oerlxe ar{} Jo (q6 sleuunJ eqf, otuata,Cpolt,C3ur ror{}o ar{t uO 'd1qe-raprsuoc selrerr qr8uel eq] ler{} pu5 IIIia sprueru,{1cJo suor}ros Jo sarros ra8-re1 B 's;eq]o ,pauopcas SeuItuBXeoq,r\ auodue pue ul -re3uo1IIr]s ro Jouor{s 1nq I qcH^e snrutdasqDl sa$aztouv lo eldruexe ouo ur ro sonrtqruSV ur ere degl su oruau,C13 'dqdrouroeotuoq euros ur 3uo1 sB eq deu sleuunJ oI{J Jo uor}Br}snlll ue d1a-reru ueql eJour eg ol ue{el. uoeq Jelau sur{elcunqdrs repurrs q}r.t&sprolr}neu Jrozoeeledo} ecuelqurosor 'euocog stl oI{} sB etEI sE (elcunqdrs leuro}ur s}r punor) sleuun; s}l Jo r{r8ua1eq} uI oruawt1cot,ItJ ssed.Insplnoc opmlv e>lrlpro[]neu B uele pue !leura]xe 'slauunJ a-redegt ,(1uo pre^r{ceq 3uo1 aneq osp (g '3lg) sa$ar,muv pue sapl.Douo7V feqf perlder oq deur 1r d;lsacue oruaut,Q3E Jo .rnoABJul ecueprle leuorlrppu sE soa? -lt[ruFy Jo sleuunJ 3uo1 eqr pereprsuoc (re6r) Jlo.,!\opurqcsJI ]nq :oruaur,C13tuo{ uoIlBAIreP e 3o ,,Qrlrqtssodaql sePnlcxa euole sonctqqo7V ur eurl ornlns ar{} Jo }uetu -dolezrap '}lnpe aql pultu .{ru o1 eq} uI sseu{crq} eq} ur :o eldas ra}EI eq} Jo srEIIoc 'qcuocolo-rd ,runceeo PUBslauun; leuoqdrs orll ur er? eJor{l se eq} ur dpeatle er{trpue 'sarnleeJ uoqdrsord oql uI sacuorogrpelqeraprsuoc sB eq deru ereql snql luelrodrur erour re; ,,{lqrssodpue rel{}o s}l }nq uot}tsod s1r dluo }ou euruexe ol ,,{;esseceusr BoPrououruv ,re,roa;ory lr eql ur enl?A IelueurepunJ qcns Jo sl elcunqdrs er{1JI
or' sreuunJ11e !paa.relua ,{1rue.rs) .elcunqdrs aq} Jo uorlcouep,",^[]."Yf;il9]t !H""JJ;i?"::l?li 'ds 'uoleq 'uopleqg ,uuluo,rapoeSl ,.ds ac srt,taco1taqCq lsa] Jo Surue4crql pue suorlcrJlsuoJ zrzzai,ClS pue 'zrureqog 'ueruorteposatrN'(epuu.lreg) 'q'u ,3uo1 .g '3lg sntaqaq{satsaJtouv Jo sleuunJ leuogdrs
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'st1otn{wt onilowtJ ur ro (q '31.f) yCnqapsontoqdaqnfl 8uno.,t eql uI uotltsod ;o sa8ueqJ oql u?rll acuecgru8rs erour ou Jo sB slsrleualsds roplo agl dq pe8pnfpe uoseer poo8 qll.tt era.,rtsazrs crdocsorclu le uorlrsod ur seue8e,rs1r 'sl1npe esec ,(ue uI lnq eql uI u?ql sprolr}neu or{} Jo ler{} o} elqereduor erour ueeq eABq .(eru elcunqdrs eql splouourure eJnleunur aql uI 'sernlcnJtrs SurpuodsoJJoc 'drgsuollelal 'sprouour Jo suollcunJ JBIIuTISoslB 1nq osolc JIOI{}dluo 1ou Surlcege: -IuB eql pue splolllneu eql uao/Kleq usrlallered lsaleerE agl sr arer{} 'ulroqs ure8e '1uql 'elcunqdrs seq (zord'5z6r) reSurlsary se reelc suroas1r aqt Jo suorlrunJ or{} 'srequreqc o] sB res1p ole JI ualo lng Surpeaccnseql pue r{cuocolo.rd eq} uea.{a}oq 'sprouotutue se aql uI sI arerll se oJII Jo epour eroJerar{} pue aduqs leraue8 eql ur 'true}srseJ e8ueqc snollqo ou sI aJaI{}1nq pu? {cH} runldes }sJg erl} pue ozrs JEInurs '(rg '31.E) Jo pue tBU requregc lertrul oql sr dluo Lou roC p"lelp ,{lecrecssr pue Ltn CIpodopU{a3ary {o uo1ru1ocaaqJ $8 L. F. Spern wide siphuncle are holochoanoidal (as in an Ordovician Endocera.s,Fig. r3a, or in Aturia, Fig. g a) and they reach halfway beyond the previous septum ; and these two nautiloid features alone would seem to suggest caution in referring this Clymenia to the Ammonoidea. The general palaeontologist,of course, who thinks of Clymenia merely as an ammonoid with dorsal siphuncle, is unaware of the enormous variety presented by the clymenids, not only in the less obvious features but also in the suture line, ornamentation and whorl shape. Hyatt (r883) already defined the whole sub-order of the Clymeniae as having characteristics so easily balanced that it would be difficult to decide whether it was nautiloid or ammonoid if it had not been for the protoconch and the young sutures figured by Branco. Now this author's illustra- tions of two examples of Oxyclymenia and Clarke's figures of the earlier Acantho- clymenia, also with an external siphuncle at first (Fig. za), undoubtedly represent ammonoids and probably derivatives of some Anarcestesroot stock. But in looking at some illustrations of Cyrtoclymeniainthe literature, e.g.Wedekind's (rgr+, Pl. V, fiS.z) C. cf . plicata (Miinster) or Giimbel's originals (FiS. 3a), onewonders whether the essential uniformity of organisation in the two orders Ammonoidea and Nauti- loidea could not mislead even the specialists. For I have before me four sections (Fig. gb) of Devonshire Cyrtoclymenia, including the keeled Clymenia fasciata (Phillips) (: C. angustiseptataMinster in Giimbel) with missing inner whorls that resemble, for example, the nautiloid Trocholites(trig. 4c) to such an extent that only the discovery of the centre in better specimens proved them to be clymenids. In other words Clymeniafasciata and its allies like C. plurisepta (Phillips) could well be nautiloids as far as the suture line, septation and wide siphuncle are concerned. But here, then, clearly all the features including the radial line, ornamentation, shape, and coiling fail to give even expert workers a clue to the real affinity of this group, and in view of the scarcity of material it is impossible to insist on the sectioning of every example of the Devonian Cyrtoclymenia, of the Carboniferous Serbclymenia(a nautiloid with a ventral siphuncle) and other rare types, to make sure of their order. It is significant that Schindewolf (rg"+, p. +z,8)called Cyrtoclymeniaangustiseptata with its slight differentiation the most frequently misunderstood and misidentified of all the clymenids. And if Sobolew (t9r+), with his large and well-preserved material, could seriously suggestthat clymenids were only intrasiphonate mutations of normal goniatites (Cyrtoclymenia being paralleled with Tornoceras)the problem of the interrelations of the Palaeozoicammonoids is not so simple as the text-books would have us believe. The resemblance between Cyrtoclymenia and the nautiloids might be held to show that if any single character of the siphuncle be used for systematicpurposes, it would have to be the width rather than the position. Only here again difficulties would be encounteredat once in explaining the thinness of the external siphuncle in, for example, IYautilus barrandei (Hauer) or its great thickness in a young uppermost Cretaceous Scaphites. As regards the thickness of the siphuncle in the later ammonites, it was at one time considered a distinction between" Harpoceras" and the oppelids, but, like the hollowness or solidity of the keel which may occasionallyaccount for this difference (sropro aql uI PelllJJ relou sI eSpe le}des og} sB reJ os ur .,(luotnq o.{\} oqt uee.&}eq ,-ra,re-Loq uorlcurlsrp Jo suEetudpeet B pJoJ€ ,(11eraue3 ,a8pa slr pue urnldes eq; 'enl€A lecrlce.rdJo eq ol aJBJool sr 'seo8 ,sprouourure ocueplle luase:d sz JBJos uorlcurlsrp IBer e q8noqrle ur nns ut ll7cf,1de;o dre,LocslPeql pue lsuorsse;dur olcsnu eql se sarnleeJsnorlqo ssol 'srelceregc qcns o1 serldde aureseql rer{lo eql IIe q}l^a uorlcunluoc ur ldecxe 'uorlcurlslP roJ posn ag ,slooqs ol olqBIrB^ ool er? reproq r{}nour orl} Jo urroJ er{l pue -So 'requeqc luBrraqB ulelrec uI uollecsrporu slr dpoq ogl r{fua1 eql osr^\e1rT 'sPlolllnBu Jo uI uBql sPlouotutuBuI Jeuounuoc,,typalqnopunq8noqf 'ralual pa,too;8 ro eloudxo uB uer{} enlsl ctlsou8erp eJour ou Jo sr uor}B}ueureuro leurpnlr8uol ro 'salcraqnl;o '1aa4 'seJnleeJ Jo BJo ecuesa-rdaq; snot.relaql Suouresuorl?lerJolur Jelrurrs Pue salluotuurB eI{} Suotu? se.^aoJeI{} se sprolrtneu Suorue dlar:err qcn{u se lsourle sI araql -ro; ide,u.le.raue8 d:en e ur dluo uorlcurlsrp JoJ posn eq uec lr uorlelueur -Euro sp.re8ersE pue 'oJII soporu 'en1en Jo luereJrp Surlcager eleurproqns elrnb ;o sr 'sturo; palroc ,edeqs ,1ce3;o eruos;o e8elscruo.ftqura eql ur ldacxe Iror{,AA lurod u1 (('stsrroeqlroJ punor8 Surlunq dddeq 8,, urroJ o1 spodoleqdec 'r(luregecun dpo eql Sureq lou salluoruur€ eql lcager d1a-reur,asrnoc 'slueruelels 1e;eua8 ;o snon8rqrueoseql ,,'apls IBJluaAJo Jalno slr uo ouoc eql qlr.^alceluoo uI Jo JBeu pece1d s.,(e.An 1e sI ]I spluourure er{} ur 1nq eldes eq} Jo ar}ual eq} reeu sr sprlrlneU ul,, elcunqdrs eql ler{} pue (sn17tnn51f,pead eqr ueq}) (. slror{.^ara}no eql Jo ( erluoc, eql 3uo1epolse{ ,(ltcurtsrp uauo are pue daap ssol ro re,AAorreu,eleulo .d ,fz6t oJour s,,(uzvrle,(1.ruau ,, ere spruourue Jo sllaqs eql 1?q] plo] eJB e^\ (6zs 'gegcnqcg) 'uorsnJuoo >poivrluacal eJoure ur'ure8y s(repeeror{} o} ppe dpo ,e8essed 'lla.{s crtd..fucslql Jo uollurlsnlll ul ua,rr8 snflnz^[ ]uecer e Suruur8eqegl;o ern8g 'snssat{utot 3o B pu€ (,,sontoutlht,,) sa\4ontonCg Jo srequreqc}sarlJ€e aql go Bur,rerp '(6frd 'rr6r 'raqreg) 8uo.t.,try ((requr€r{cdpoq,^aoller{s B r{tr.{apuu ,req}e8o}asop (lueureuro 'peo;q ,1roqs dlerrrlelereldas qll^t leurpnlr8uol ? qlriw uogo e:e (eeprol 'a't) -llneg qcuocolo-rd B lnoqlr/K esoqtrl-requreqc f,poq daep 3uo1 e qlpe pue ,gede 'qloouts ',{aor;eu '3uo1 :e; dllensn eldes glur ere (eaprououruv .a.t) qcuocolo.rd e qlr.{a slloqs pelroc d1:ee eg},, ler{} pe}e}s uaeq rer{unJ s€r{ }I .pelonb d1p-raue8 'sa8pe 'srelcureqc oslB orB rIeI{} pue eldes el{r Jo uorlern8guoc eq} dlqelou rer.{}o uI secuereslP lnq l eaplouotuuv pue BaplolrlneN srepro o,AAleql Jo uorlcurlsrp eql ecu?Uodrur uI .(.ruurr-rdJo oq ol ue>lel ueeq a^Br{ degl esneJoq lre}ap ur poJeprsuoc ,elcunqdrs ,gcuocolord uoeq el?q slrorl,/v\,(1-rea er{} Jo Surlloc eq} pue eq} eq; 'srapz,ruqr ,raWO (t) 's8urdno-r8 roulur ,ften ueql erour roJ elcunqdrs eqr Jo ssauTJII{}eql osIII}n ot saddl Isuol}Isuerl .{ueu oo} eq o} uraas erar{} dleleunpoy -ufl 'alcungdrs snntoyCT leurelxe repuels oq] ser{ osle ourl arnl.ns so,tact.tpnog s1l safiDun,mA'eeprltuuelq '.(1pue; qll^A cr1e1.(qdr(1ode ur s{ro}s rer{to Jo s}oor{s5o pegrldrurs,(peprurs qlltt polelcosse dltce.r.rocurueeq e^Bq ol u^,oqs eq dlqeqo.rd 1p.,r,r, 'elcungdrs 'saprua7o,t 'crlsrro}cersrlc sap{otg s}l q}l/a d. ol1{,ln..roy orour eg o} a,ro;d deur suorlces uulpetu ul sJeleurerplleurs le sseu>lcrr{}J€lncunqdrs ur d1r-rupurs}Brl} 'pue,{ 'elqrssod 'sasod.rnd rol{lo eq} uo sr 11 crleura}sdsroJ enle^ Jo po^ord 1ou ser{rl 6tn opo{o1or1da3ary {o uolru1oaaaqJ 4+o L. F. Speru nautiloids. For wavy or angular suture lines occur in nautiloids as much as in ammonoids, and while the septal surface of a Devonian Anarcestesor Agoniatites (trig. ro) is plainer than that of many a nautiloid (Fig. 6b), the complicatiln of the suture line in, for example, a Gonionautilus exceedsthat of many goniatites, cly- menids, or even certain reduced ammonites, Triassic, Jurassic,or Cretaceous. I have discussedthe value of the suture line on a previous occasion(r9r9, p. r7il though mainly in connection with the Ammonoidea, and I can only reieat that even if we place the suture line first, for systematicpurposes, it can only be .rsedin conjunction with the development of all the other charactersof the shell. Applied to Nautiloidea, it thus seemsto me that the suture line of an Aturia is of .r.. i., indicating-.rr.n its prob- able derivation from a hercoglossid; for the siphuncle may be internal ir, u young Cimomia (which, of course, I do not take to indicate recapitulation of an
fiq.s. a, section through inner whorls of Aturia aturi (Basterot), Miocene, Turin, shorving internal siphuncle^and long funnels (xzo). b, Cyrtoclymeniafasciata lfhiilips), Upp"r Devonian,"shaldon, Devon. section through siphuncle, showing long funnels (xro). loriginuis.y ancestralstate) and the long siphonal tubes of Aturia (Fig. ga) canonly have served to weight the shell. IYautilus itself persisted almost unchanged alongside these specialised offshoots, and since it has been considered a very primitive type on anatomical grounds also, we may accept not only a simple septal .ag. and a clntral siphuncle but also an unconstricted aperture and an open apical cone to represent original features. So long as the function of the shell as a hydrostatic apparatus was not impaired, it mattered little in what way the changes in specific gravity during growtir were adjusted. In each of the two examples of Aturia aturi which I have sectioned,the first three septa were very thin and the fourth of abnormal thickness, while even in the recent l{autilu.t an occasional septum (long before the last one) may be twice as thick as its predecessor,to be followed again by a thin one. In Glyptophicerasminor one individual may have only eight septa on the first z] whorls to thirty in another, and I have previously discussedsimilar irregularity in some aclult ammonites. I may only add that in the youn g of Arnioceras nigrum, one of the species previously oI IIIA u s 'otlv 'satcads seqol o/\u selurleluos aurEs eql puB ouo Jo sorlarJB^ elnlo^a puB elnlolur ur ?ueJegrp ueeq e^€q lsnu lueurdola^ap qcns ro; lspog.{a elrsseccns Jo 'ornlns lceluoc Jo eurl eqr Jo eprstno ro oplsur lsnf ro l?rrlrqurn eq] tB seqol .,rrauJo uorleruroJ Jo epour lcexo aql ueeq a^BLIlsnru eroJerer{}acuulrodrur ssal III}s JO 'aJII 'a't';egrnerqc Jo epotu aql ur a8ueqc lcurlsrp d;al e f,poq or{} Jo uor}BJgrpotu pue Sugre.,rrpdq paruedruocce sde,nle se,ry\se}ruourure 'seqo1 ul ad,$ crlrluruoE ? ol uorlcnper pue i acuecgru8rs 1q8r1s,{rerr go s?,{a}r ;o 'sa\4oncopnasd 'f,'a 'salppBs Joqunu eql ur essoJcurue ,,{qpelesuaduoc sBl!\ ur aq} Jo .'lunper8 u
III. THE AMMONOID ANCESTOR. It is an established fact that the earliest goniatites only differed from most nautili in the closer coiling of their inner whorls; the position of the siphuncle, which be- came permanently established on the external side in goniatites, is of minor import- ance although it led to differentiation of the ventral portion of the suture line, or, at least, became associated henceforth with the region of greatest complexity of the septal edge. Zittel was thus perfectly justified in laying stress on the insignificance of the differences that separated the Ammonoidea from the Nautiloidea and it is apposite to recall that in the last edition of his Grundzilge (rgz4), undoubtedly the most widely used text-book of palaeontology, it is still stated that it was entirely uncertain from what form, or more probably rvhat forms among the Nautiloidea, the Ammonoidea were to be derived. Frech (r9oz), also long after Hyatt had pub- lished his theory, regretted that the late appearance of Bactrites (according to him possibly a secondarilystraight shell) did not allow of a decision of the problem as to whether the ammonoids were derived from straight or from coiled ancestors.The z-ot 'ruJoJ rBIIruIs,t11euta1xe Jo sellleluo8 ur se ,{1}cexapcgrpou sr sessoro-rdlereqdrred-ore1e1 Jo srolue.t reln8uelg or ,{cuapuel B eAEr{r{c5{^a sprolr}neu ur aurl IBrpBr eq} A{oq '(IIIX 'ld 'tl,gr) '(t '3S ,III .ld ,o69r) ^\oqs III,K scr,rosrsfotr\lpue elerueg ,bLt .H 'LLgr) epuerreg dq paqsqqnd sern8g 's.lagto Suoruy 'luelrodurrun osle e-re(snurs 'spJBlK{cBq cttuouod,(t1e qfr.tt) ql.Lro.r8Jo seurl er{} Jo esrnoc oq} ur secueJegrpeqJ Euqurod {ceu pldas s}l tl}llnr('1's sontoapuz,rrtvg'a't) spgvrac.,tqdr4 leur8uo eq} ur 'elcunqdrs (uosspeora) leprouuoqcor{uoro (alsraog) pprouzorlJoloq eqt Jo ern}cnr}s '(or '3rg) 'dleuorsucco aql uI ecuereglp lelluosse ou sr orarll suorsueurrpa8rel .,fuerr '1o sag4otuo7Vueluolee alppl6 pue roly\oT relrurrs eql uro{ srolcerer{c IBuJe}xaur ,(ltq8qs 'elecunrl 'pesse;dtuoc d-rerrragrp eqol lerat?l p€orq qtr^a sllaqs esaqt Jo ouros
('zz-rz's8g'IIIA'ld'S98r 'epuerreg reUV) '(-!x pacnper) sernlns aldurs qlr.r,r,aur1lno .erruar{og 'snrderuoy ruor; atr}Bruo8 (ueruolaq re,!\o1l ,{1-reeue '(apue.rng) sqap{ sal4loiuoav .or .Fr}
'dnor8 'snntoapuzrttog uBIIIlnEu uBIrnlIS enrl auros ,(lareur pupr ur per{ 1 rl}lrla 'u,lou4 sa\4otuo7y lseIIJBaoql SullslcosseuI pue ,{1e1e1duocur,(-rarr 1e,{ se oJBrlr}ngu 'rarre.tr.oq'.,(leleungoJun pelroc uerrnlrs 'seSueqc pelulorroc oql ore se ,olqrSqEau .8tg) sr ileqs prouolurue enrl B olur elcunqdrs lBrluo^ qrpa (t snncdqd,m,l elll '}q8ram PIolItnBu B ruJoJsuBrlplno,/v\ lsql SuIIIoc Jo oseeJcurl{3r1s eql roJ ou sorrJgc ',{ep '1utod 'sa}r}Bruo8 luesatd eqr 1e sry} uelg ueruorraq aldrurs eql qulr uoururoJ ur erour Surqtou PBq pue uoltultruereglp Jo eer8ep qBIr{ e peqceor dpee.rp perl rlr}ngu uslrnlls eql lEI{} se/v\^\eIA lsrg er{} Jo rno^eJ ul aq o} urFI o} peruaesl"q} lurod dpo tw upodoluqda3ary {o uopruToaaaqJ 444 L. F. Spers
The genus Barcandeoceras,as founded by Hyatt in 1883 b. zgg) was compre- hensive, but was later (t8q+) included in the family Tarphyceratidae, characterised by compressedshells with more or less ventral, tubular siphuncle. Foerste (tgr;, p. 7) suggestedits inclusion, at least provisionally, in a separatefamily Barrandeo- ceratidae on account of the more central position of the siphuncle. But this cha- racter is not of generic value, in, for example, Tarphyceras itself, and sometimes not even specific (" Orthoceras" koninckianum d'Orbigny); and without sacrificing a number of valuable specimens of these nautiloids it is impossible to demonstrate
Fig'rr' Barrandeoi?f'"1*T{#{,u::;:i1?,;,$"YJff:,tlft:itl"**fii:ru,l"lXiaoutrine'
afresh the vagaries of their siphuncles. In any case, the late Bohemian forms such as Barrandeocerasbohemicum, here figured (FiS. lr) and included by Hyatt in his genus, may perhaps be separated generically from the earlier costate type which according to Ruedemann (19o6, p. 45+,Pls. XXXII-XXXIII), occurs in the Chazy Formation (Lower-Middle Ordovician). The siphuncular structure of many of these forms, however, is not known and the transfer of " Barrandeoceratidae" and other types from one sub-order to another, reflect classificatory chaos rather than a rn'orkableapplication of Hyatt's elaborate if superficial scheme. Hyatt himself traced the Silurian forms referred to Barrandeoceras(of which at least B. bohemicumhas an annular lobe) back to their Ordovician (Chazian) fore- runners, and they do not really differ more among themselves than do species of
L- .safiqnqogo7 sHI snua8 rrreu aqt snruu?rurg roJ Pal?orc snql Jlo./v\epuqJs pue 'sreer( uautouB l{SnoqllB | ,,say..tycog,r Ia adft eqr srql o{Eru o} sureos oulu JoJ wnpnu ,raE.raqpues 'g) dq (sncruocqns olcunqdrs leur8reur qll^\ Pllsreroqlro uB Jo uollueur 'g ereur al{r fle]€un]roJun 1nq 'ed,$oueE eq] eq o1 (qce-rg snc4dq1a : reEraqpuug 'sturoJ asor{l snlouutorg) ,,safq?og,, eutnua8 euo sil{1 4oof ,(1fduo;d qcard olvU uoISSeJduIIerrres aql ;o selduexe IBnlcB eJedruocorl^t IIB dq pereqs eq dlqeqord 1p.,r,r (StpJDrE pua (,,sOnJoMtW,, :) sarylura?onCgo7 .(snlvut,tOJSaPq?Og,, Jo ecuzlquJes 'des 'selluottlurc o} -oJ eql ,tq 1cn-rts eJe,{.sJelJosqo asoq} o} sI }Bt{J palloc uIBlJoJ prp saplwog lqBrcrls eql se snssatdutocsapl.otuoC ol drqsuorleler aru€s eql uI pools 'sreqlo 'qcrrr(eg 're8raqpues (..safi4rog,, pue'(zo6r) qcerg Jo uoudo er{} uI .NOIJVTNJIdVJSU CINV,,SgTIVtrCVg,,'AI
'ocuereeddu 1s-rgrrel{l reUB s>lcolsprolrln?u qse{ ,(q peqsruelder lou ore.{aBePlouotutuY eql }Bq} paSSIIBS 'a1ero;red trs3JuBc e/v\l3r{} os pue esoqolS eJB uBllured pu8 snoreJluoqJsJ aq} uI 'sodr(l se8pe pldas eldturs qlu( sdno.r8 qloorus eqtr.,{re.r}uoc eq} uo ellqr!\ ezrrlrtutrd 'lll}neu 'sernsod eJBpue seurl eJnlns eldrurs oABr{'rala.troq JaIBI pue cISSBIJJ}so6 oql -xe elqelrns Jo {cBI o} Sumo ureqtr lcalloc ot ernlIBJ o1 .(lereur enp sI cIteBI{U ur asdrlca lueredde Jreql ler{} Jeolc sr }r s?rT Jo,{aoTer{} uI ute8e luepunqe eJBIIIlnBu ,lng eJurs l Beprouoturuv eql ol ((IEIBJ,, tsourl€ sE peqlrcsep uoeq ,(11u.raue8sEI{ 13r{r porrad e ,crleeqg eql ruo{ u./v\oulun ^,{1el1ueeJB splolllncu IBI{} }cBJaql esrszqdruo 'lloqs 01 areq al${rA r{iloil eq ,(uur 11 3o sedft o,^$ eq} uo aJII Jo sopotu TBIIIUISJo 'sproplneu lceso Julrurrs e Su4ecrpur ,(lsnornqo pue splouoturue ,{reroduraluoc eq} luaurdolo^ep eql ur tusrloller€d 8uqu1s oqt ol patrerlp ueeq dpeerp seq uollualle ;o 'sptolt}neu pue I u€rJnlrs reddl aql ur eurJe luel.rodul eJour pue trsrg er{l reUE 5o erusB puoces B r{}r1y\peprcuroc porred crssBrrJ reddg aql wql pelurclc d1rg8u uaeq .alcrpur 'saut1 53q 1I elruourure Jeqloue pacnpord roleu oseql 1nq eJnlns ctltletuo8 ro selcunqdrs leur8reur reqtra padole^ep qcrq^\, EepIolItnBN eql Jo slooqsso relul 's.rolsacur dueu eJB eJeql l?ql ppe detu 1 prouoturue er{} su pepru8er eq o} eruec (,,sontoun74,, :) safilon?ot{g pue s?U.tlrog Je}31eql ^\ot{ Surururuxe eroJefl 'sJeuunJeJoJ . Jo serrerodureluoc pillnuu rreql ql1.tl. saltleruo8 lseI[JBo eI{} SuIlBIcossBlsute8e '1r 'qcuocolord luaurn8re uB sE pesn aq uec pesnec 1?ql EuIIIoc Jesolc el{l Jou 'esec '(a '3rg) ,tpee eql Jo ruroJ er{t rer{trau ,(ue u1 S sryxtnol{ }uecar eI{} Jo srequ?qc aql puu (salcungdrs elqrrJea,fua,r qlr^{ Breue8 om1) sv.Laiotuolsfl'puvso.ra?onpao,tqrs sagerodureluoc uercrlopro aql Jo seuoc pcrdu aql uee,/yueqSurlslxe luq} sB esolc 'pauorlueru sB selrluruo8 dpea Jo osogl qlL!\ truotuear8eu? l\oqs uaeq ,(pearle seq 'ofnlorrur se,(ot'8tg) t[apas sonctqd,tCIJ lo slroq/v\rauul eql ,(1e1s1durocsB roqtne stl f,g peqrrcsap ueeq s"q r{crq/v\(elcunqdrs lerlue^qns ro IBr}uaA q}FA) reporr{cs 'elduexa 'sr 'euIIcaP sar.wotstctzg' snueS usrJr^opJo Je./y\oTorll ro5 a.leql aql '11e '}eqt uo eJe,trrsprolrln?u eql 'pJe1y\uoueruoleq Je/v\oTel{l ulo.l; ragu raquroureJ 'ueunpg '.re1e1 ol ila.{A sr lr puu l sruro; oql aJB uaqtrtsanlo4uo7y e>lII erour qcnul 'sraquteqc ,(lluuorseccoaJB snua8 prolrlneu srrll Jo sJeuunJeJoJUBIcIAopJO oI{} I€IlruI 'sptacoapuo.t.tog 'esec 'II}nBu Jreql ut Jo uorlulerd.retur er{} Jole}eqrvr ,tue u1 Jo}u[ sw opodolotl{a3 aqt {o uoltn1o(LaaqJ 446 L. F. SpnrH
change may be regrettable but it does not really reflect more than the inadequacy of our nomenclatorial rules. Moreover, the restrictio n of Bactrites to the subconicus group makes it a synonym of Ortltoceratites Blumenbachl. No doubt, this has somewhat ,, cleared the air, for there has always been confusion between this Bac- trites " and I'obobactrites, not simplified by the subsequent discovery of very similar protoconchs in what were believed to be the two groups. Let it be clearly under- stood then, that there is one group of " Bactrites'l (now renamed Lobobaitrites) in which there is pronounced bilateral symmetry and a peculiar dorsal keel, oryuih.. raised band. The ornamentation is very fainl ventraily, as in some Gyroceratites, but it is more distinct on the two sides of the dorsal band, and strongiy projected backwards, like the septal edges.This whorl shapeand ornamentation-cio..ly ugr.. with Eubaculitest:agina (Forbes) in which, however, 'fhere the siphuncle is on the oppJrit. side. is no resemblance of this ornamentation to t^hatof forms llke Kokenia obliquecostata Holzapfel, which Correns has now shown to be a nautiloid; and even such angulate orthocones as Goniocera.rare not in the least comparable. On the other hand there are the so-called " Bactrite.s" of the .subconicusgroup (Ortho- ceratites) in the Wissenbach Orthocera.s-Slate which have a .iruight septal edge, the siphuncle often not quite marginal, and the general aspect of Orthociras, concavesepta :'.e' and a more or less ciicular cross-section.And all the supposed " Bactrites " protoconchs hitherto found may belong to this group, i.e. to Ortho- ceratites. it might - _Now be askedwhether these differencesare really sufficient to separate Lobobactrites, as presumably an uncoiled goniatite, from the orthoceratitid ,, BAc- trites," i.e- a nautiloid. In this connection it must be rernemberedthat thesestraight folms lived together in exactly the same environment and that the orthocone shell reflects nothing mgre than adaptation to a similar mode of life. But apart from this functional resemblancethe convergenceis accentuated by direct relationship; for it has been shown above that the early goniatites are still closely related io the Nautiloidea 'l-riassic and we know from the occurrence of genera like the Rhabdo- ceras' the Jurassic Acuariceras and the various Cretaceous baculitid forms that the possibilities of variation are extremely limited, even after the suture line has taken on frilling. Let it also be noted that there are no passageforms between the straight Rhabdoceras andthe.spiral Polycyclu.s,between A-cuaricerasancl,the coiled Spirociras or StrenocerLs, a point of some importance. For Hyatt considered that those rvho sought to claim that Bactrites was a " degraded " form of. " Mimocerils" should. produce forms of the latter, and of the origin al Anarcestes,in which the adults were uncoiled, after a close-coiledstage of growth had been passedthrough. Hyatt went on to say that such " degradedforms " were common in the Jurassicand Cretaceous, and enabled the observer to connect Baculite.swith the normal coiled ammonoids of the same formations; but he could not have named, and it is impossible at the present day to name' definitely and uot just vaguely, such transitionuf typ". because they do not exist. 1 Genotype. O' gracilis Blumenbaclt, SpecimenArchaeologiae Telluris, r8o3, p.2r,tab. ii, fig. 6, a species rn'ith almost marginal siphuncle.
i=- 'alcungdrs relczrgl{c clreue8 B tou aql Jo uolllsod aqf ur ,(1e-laruPeraSIp pu? {cols 'ecue podopgdoc lseuoururoc pue lu€unuop orll Jo sJequreu ,{1duls oJe^{,f,t.{;, -Srerruoco1 ,(lararu lcedse son?oquo rreql pa,^aodnor8 snruwqns uEIuoAeO elppl6 'clsseuJ ueeuerrellPe6 er{} puB oql Jo sruroJ ar{} l€q} elqeqord urees lou seop }t rrczoee1adretel eqf fnoq8norql szaroql.to Jo ecuepunqe eql Suueptsuoc .e\oNI .euo 111uel lseel 1BJo uoruodord agr ur seuo pelloc er{trro^o sploll}neu lq8rerls 'urnesnry eqr dq pa;tnbce '(1}uecar aql Jo eJueJepuoderd B llrls sr erer{tr qsltlrg ,o.r8euatuotrN euros Suoure pue Brusofl Jo sEuJ elppl6 aql tuo{ spodoleqdec ooof 'SIuJoJ (PIolI}n€u ,rtlpurg (.sap.q?og,,rel{}o q}Ila luBuIIuoP eql sI sunroql.Lo'r(llJlg 'solruoururz .&\eupelrs}s eseq} pelsed Jo u3rurred rel\oT eql ur ure8y Jo s{co}s }Bq} -fins .rarraeuo ou pue iuoseeJ snorlqo ou JoJ sBIJI egl Jo plolllneu polloJ B seoP os ,qcuocolord 'lerlueJ 'leut8Jetu 1nq uello./v\sB olerl osaql Jo eruos 1ou elcunqdrs eqr 'a't esaqt qlptr Slooqsso euleJlxe ,,'sa7l,tlJag,, pellsc-os aAEI{S?unBJ sanJolll'to qclr 'lueuluopa.rd 'sexel luql elou ol ]uelrodul sl pue dle8rel ere sllaqs lq8re.r1s Yo IIB U 'srvrou>1 uorleurJod ocsrJ eql s€ qcns 'sno.reSruoqJeJreddgl euIJBureql ur sB IIa.IAse 'euolsarulT 'epuBJJ€g lsrEoloe8 ,{rene su SnoleJIuoqJBCeq} uI ,(q ,, rtlueJ E Palpc 'ureql " Sureg Suoue uJoJ p.rrds lseuoururoJeql ,,'sn,ntonCg,,polloc ,t1asoo1eql ueAo ,sproplnru palroJ aql ueql ueruoloe er{l uI }uepunqe orour -re; ,(1anr1e1e.rare .(aq} ,urrpuelr{}oC er{} pue oq} Ir}un uoururoc euoceq tou plp sruJoJpelcunqdls-1y\orrBu ,uurcr,ropJo eql ur pelsrxe sonroqtto euros g8noqrp tet{tr }sISuI o} }ueuodurr sr 11 'selcunqdrs .son?ollltO arul drerodtueluoc erll uror; alqerudesul or€ 1a,( ltut8reu 'O e^?q qclq^a 'orellaurure1 asuauolrpo ro touta\od'O uzlurrad orll pue (qrrulg 'septsag urrred .f) ranc.touoq.rzrso.ta?oUl.ro snoreJruoqreJ reddq oql oJ€ orer{l 'alcunqdrs 'san.qroqopld s\uBl{l ((sapUJOg,,uEIuoAeCI eql o>lIIeJolu l{cnlu ,(11eerst 'splouoluru? purS;eur qll,tl ,so.taco.tqcoguellnuopJo aI{} reloarotrN Jo Jolsocu€ aq} 's;eqtuuqc ur palcadxe eq plnoi!\ ler{ra dlec.lecs rIB roIIJee aqr Sulppeqs JaUB xede 'solcads '(}z-r 's8g s1r pa.lredar uele r{clq^AJo reDBI eq} pelecunr} aq ot ueddeq 'd 'IAJXJC 'ld '898r) epuege[d utnraoto.rnald'd puB unaprc\t\s ^\oNI (('r{cuoc 'pelldrur -olord B puq osIEsau4?oqop,td tur{t pe}B1sdlrrcrldxa lou q8noqr sB^\ 1I,, 'mBr(H) l?q1alrr^\ o1(SS'd'6r6r) 3ue1 pel (grS'd'oo6r srsou8etpssalSurueou ot{} 'erueu 'sap4cuqoPtd pue i son?oquo ue ,(1uo sr osle arrtlseS8nsstrI Jo elrds ur lng .elcungdrs (uuunlrs 'epuer roJ pal?oJc I€uralxe qlr/v\ oql yo reg unapxo1ftsson?olll'to '3'a'1uer 'saLt\o.tat ,lledH sap,tpoqo4ot4 cuaue8 uaar8 ueeq aleg aseql Jo srel{}o 'elcungdrs -oql,to uro{ gedy 1uur8.reussel ro erour e I{}I^\ setcadsetuos pecnpord 'uourtuoc 'puuq s.f,e.u,1uscq 1l eg ol ue8eq sv.La?olltroaculs .lale rel{}o eq} uO 'sercedsJewl uI '.requreqc 'rrrerzr slroq^\ Jerlr€a ,(larusseccnso1 Surpeerds ueql pue dpoq eql uo lsrg xoporllro eql qlr^\ ecusprocce ur '1ou pue .{peppns slooqsllo prle.lecoldl snoace}erJ 'sap4ntt3 'puu 'setlle esoql ur pedoleAap oq ,(etu uollzlncJaqnl uale uI SB SII PUB 'regur€qc wnaa{o,t1ur ro '(t '3tg) a^oqe peuorlueur se'sa1r,qdor,Sul srncro eureseI{I o} 'ctltuotuuru dpoq eql Jo rerzorc IBuS eql pu? UBr{s }g8rerls e ur ute8e llocun 'procrlaq 'esoo1 seuoceq trr eroJoq uele pue eq deu slJol{,{areuul aq} Jo Surpoc aq} ';eremoq 'osec (z .Bv,Axxx .14'szfu,gledg) sonto7c74lelrl ruroJ snooc€l?rc € Jo eqf uI 'eJueplle coq n4{otd o7n coq tsod uo peller }}Br(H }3r{} ueos eq ily!\ 1I LW zpodolurl{a3 ary {o uoltr(oaa aLlJ ++8 L. F. SpnrH in other nautiloids and not even specific in other " Orthocerus." Conversely Lobo- bactrites, by various features and especially by its suture line and septal surface, shows what Hyatt and others called " close affinity " with Gyroceritites gracilis (: " Mimoceras" compressum)and thence the goniatites. So that, allowing ior the more pronounced difference in the septal edges, " Bactrite.r" and Lobibactrites (with unknown beginning?) are probably as distantly related as are Rhabdoceras and an Upper Triassic Orthocera.r.The view that evolution was necessarily from straight to coiled, already shown to be contrary to the evidence, was, however, based on the supposed recapitulation of an ancestralorthocone stage by the young of one spiruliform goniatite, namely ., Gyroceratites(: Mimocerar,;1 TrirnAui. Thi" view, of course, seemsto me to be entirely untenable, and since I have elsewhere discussedin full the unreliability of such recapitulatorial evidenceit must suffice to state that it is not theoretical considerations but practical experience that has taught me to disregard it. On the contrary I am now accepting it as a matter of course that in ammonites at least ontogeny is not an epitome of phylogeny and that new cha- racters appear in the young and only afterwards encroach on the later whorls. Without going into all the evidence again, I may briefly recall that, as uncoiling in the Cretaceous genera mentioned above began on the inner whorls, so the keel in Quenstediocerasand other cadoceratids or the groove in Schlotheimia and in Berriasella first appeared in the young; and the spines of Asterocerasor the run- cinate periphery of Kepplerites were caenogenetic, i.e. they appeared as new and not inherited characters in the early stagesand were fully aevetoiea and persisted to the last whorl only in the geologically later species of these g.rr.r". It is clear that if in Gastrioceras the tubercles appear (caenogenetically) to support the depressed early whorls, and the same strengthening device is adopted by^many a later stock, the mere possession,bY a given shell, of coronate inner whorls i, ,ro indication of derivation from a coronate ancestor. The same applies to all the other characters of the shell and even to the septal edge. We have been taught to deduce descent from the individual development of the suture line and although I have myself used such recapitulatorial eviJence, I now consider the recognition of so many goniatitic stages in, for example, a Cretaceous ammonite to be as meaningless as is the hypothetical skipping of some of these stages in other Cretaceousforms, for the suture line of all ammorrit.r, during growth, has to modify by degrees. Looking at the ontogenetic development of the suture line in Pseudoceratites,e.g. the engonoceratids, recently (r93r, p. ::g) discussed,I do not expect to see arrestation at an imaginary ceratitic stage any more than retro- gression but merely modification of a hoplitid suture lin{ comparable to that of Anahoplites though of a different type and of course appearing u. *o^ as mechanical considerations necessitateor allow. This flat and s-ooth form, with its asymmetry and extraordinarily long range undoubtedly led a mode of life difierent from that oi the other ornamented but short-lived hoplitids, and engonoceratidswere similar adaptations. Another Gault form, Moisisoaicsia,wasdescribedby Hyatt (r9o3, p.25) as probably u " Cretaceous member of an [unknown] primitive stock ;hi.[ f.gu" with Psiloceras in the Jurassic." After a lifetime .p.nt in elucidating the laws of
\ '(z '3tg) elq€rrul oq llrts ,(eur a8etrsdpea oqt sa$ntDuv pepoc ,(1eso1cerour eql ur 'asBJ 'pue ,{ue ur luelsuoc }ou ,(1quqo-rdsI }I lnq ,,'sa7tt7?oB',,uroJJ uoIlBAIJep JnoABJ 'qcuocolord ol ruees tou saop slqJ aqr ruor; .{ene lroq^\ B Jo prlq} B }noqe selr{. 'dllenper8 uorlces-ssorc lselptus eql lurll os .,{1uour les Surlrorruu }st{l pue a8rq p1s erel\ qcuocolord eql uo SulnolloJ sraqurur{ceerq} ro ol\l erl} lerl} pa^rasqo suq Eraq 'sapqotuo7nwlry 'ra,roero6 'Suruado 'poqrrt -uaqcrg sH ul ou lnq lsrg eI{} Jo {upl e dpo .{,oqs peuor}Jes a^€q I tzr{} sarcedssry} Jo selduuxe (dapnqolg) uururaqog anJl euros szaJerl.{a's1;oq.Ll reuur pro}BJecow1u qllll surroJ (apuerrug) sncrutaqoq 'suor}eroJrad sap4ntuoSow?Wol seqrrcseroqlne srr{}}eI lecqrqtun el€q 1e,{eu ,teqr 'aarlse88ns 1nq 'passnJsrp a9 ol u,ry\ou>l,tlaraldruocur ool sr rana,u.oq'(nef,y1 sa74 -otuoSoaogod:) snnpl sa!.lotuoC s(apuerreg a{ll 'lsu1 eql 'saqcmqdsourllAlpuv sapl -ntuo3owt741ereue8 ,l\au o.4ll 1nq'sa4saJtou7 pue ,, su'worutry,, ^(1uolou uuluole61 'seuocrlnneu ra.^aoT er{} ruoJJ paqrrJsep ,(1a1e1suq (rt6r) Srequeqcrg lBrtsecuB 'rcrltqwn aql ol rBeu os ilrls sruroJ ur palcedxe eq plno.tn,]Et{^a dluo sr srql pesolc 'ro}seJue ,{ltce;radurl peq lsrg tB sa}rleruoEueruo^oq JI r{lootus € Jo uoll€lnlrdecar eql uo poseq sr lr sBr€J os ur'r(ce11ega8nq euo eur ol sl ,,eBpItreIJVer{}Jo sISaueC,, 's.r,re1 snl puc IBJnleu lou oJB pultu dur ol palelnlsod 11er(g legl ,, s,{aBL,eql 'Jrle?q6 aql ur splouotutuu a{l yo asdrlca leraua8 '1co1s aql Surrnp pe.readd?slpU q8noqrle Surqsrrnog B tnq ellues B tou pue oJII Jo 'xes aporil lurceds B ol uorleldepu ue ,{1.lee1csat so.nrotstnqJ o} dlaretu pa}nqIJDE 'sncstptlsoJ 'sa\tqdots uaaq ser{ ler{l acuere5rp v pelrocun eq} qlr.^a pareduroc se -o,trory ur requr€qc ,(pog aql Jo uorlecsrporu or{t ue{l ssal IIr}s .{lqrssod segru8rs '3rg) soia?olst,roqJp slenpr^rpur ouros ur slrol{^{, relno eql Jo uottre.redasoql : (r7I 'so,tacopqo?u eprs l?srop eql uo un{l lleqs sll qly( lr{Ere.rlsaql Jo ro}secu? eql lou sI son?olst.toqJ c$serrl ar{l dlesrezruo3 'Surrdsgo pollocun pacnpord relou }suel le 'sprlndres '(tt1 '14 'zt6r) 5o gl.tro.r8aql o] enp ro 1ecr8o1oq1ed.,t1ereru lou JI e8uel '('"tt 'ITX pue (IIIX 'ld 't88r) rparsuanO fq parn8g sorarorutv elnlo^e eI{} ro 'XIX 'IIIA 'q4 '6l,9r) sEu,(ag .(q pelerlsnllr setrruounu€s€IT re^\oT raqlo pue uotn 'pleq 'lroqlr so"anoLrJo>lrl s{uroJ tnq DEIH se re]no eq] uo ur8aq .(etu Surpocufl 'Euoleq sraue8uoc pogrpourun sll qcl{ra otr dnor8 eqt Jo sro}cer€tlJ aq} /Kor{s ,,(1ereu 'uuog 's11eqs 1nq luJlsacu€ uB ,. a1e1'rlrdeceJ,,lou op elruorutuu IIB e11 qlltror8 'sturo; 'JeqLuBt{O qtrm SulSuer.lc pegrporu r{Jns Jo slroq^\ reuur oq} spJo./v\Jeqlo uI 'suro; fpoq eql Jo uorleOgrporu B ro uorl€lueureuro Jo ssol pesnuc ,tusur w lleqs '}1npe or{} rolo Surqceer ol}u€tu oq} q}IA sdzqred oqr Jo aJII Jo eporu eql uI e8ueqc 'lueurdolelap 'alduruxa 'snoeczler3 B leql alqugord sr lr pue leurrou sI srql roJ ro^\oT uelo pue cISSBrnf reddfl pue olppl6 eqt Jo soatoprCq{oqtft1 Eurrrlo,re '{co}s dlrrols oql ur sv lertsecu€ aql Jo sre}curerlc sunropl?H eql ^\ot{s }BII} suolt 'p;rg -nlo^ JerlJEeeqt ,(1uosr 1r pue EunoL sntou',I2Jqns(.snIxlnDIV,, uI ecuBlsulJoJ 'dlruge lpegrpou dn81q eq deu tlnp€ aqt roJ crlauaE Eutlee,rar roJ sselesnsdervrle are 'a8els qloous ,{1-reoeqt ratJe 'spoqll Jeuur eq} }Brll dldun }ou saop slI{J 'snollqo st so"nco7o{tg pelea{ d.lerodue}uoc eql q}r^\ snue8 srql Jo fi1use eq} suollureplsuoc pcrSoloqd 'seltuotutuu -rour eldturs uro{ 1ef,'.papznd f,1e1e1durocsern per(11 uI luarudolarrep 6tr upodoluqda3ary {o uognloaaaqJ 45..u. L. F. Spern while Sandberger's(r85r) figures show that even the Upper Devonian Gephuroceras and Manticoceras may be perforate. Yet Anarcestes represents a progressive stock and if there is any connection between Lobobactrites and Gyroceratites (or " Mimoceras") then it represents a " degenerate" branch, originating in a form with very unstable inner whorls, as clymenids arose from a similar group in which the position of the siphuncle was unstable. Lobobactrites appearstoo late to be a radicle of the Ammonoidea and the orthoceratid " Bactrites" that existed from the Ordovician to the Permian never showed any coiling, except, possibly, a curved apex, like the specialised, Poterioceras. Moreover, an involute and oxycone form like Pinacites, existing already in the Lower Devonian fnot to mention the still earlier Silurian Agoniatites desciibed by Denckmann (r9oo) and tl-re Eodevonian Tornocera.sand Epitornoceras recorded by Frech Qgoz)l clearly shows that the tendency to uncoil (in the Lower Meso- devonian) was preceded by a long period of more and more complete incoiling of the Ammonoidea. All the Middle and Upper Devonian Anarcestes,Agoniatites, and Manticocerates which I have examined were closely coiled, with only sometimes a kink in the first whorl (Fig. zf); and.while there is no reason to doubt rhat such perforate individuals as have been figured by Sandberger (r85r), Holzapfel (1895), and others, did exist, the tendency to ever closer coiling or greater involution be- comes evident in the Carboniferous. Like the modification of the protoconch from asellate to latisellate and then angustisellate so the gradual incoiling was slow, com- pared with the rapidity of uncoiling in the aberrant offshoots.
V. THE PRIMITIVE CEPHALOPODA.
It is desirableto give a brief review of the principal types composing the earliest cephalopod faunas if a picture of the development of the class as a whole is to be obtained. The great majority of the early curved and straight forms had a large siphuncle which often contained part of the viscera as is evidenced by the muscle impressions. Some had an apical cone (Fig.r3a) which was either short and strongly inflated (IYanno) or long and tapeing (Proteroc.ameroceras),and Grabau recently (rgzg) again echoed the opinion of Ruedemann (r9o5) that these forms which at first had only a siphuncle and no camerae (i.e. air chambers), were the most primitive of the holochoanites. Now Hyatt did not see in the large, inflated, apical cone of Nanno more than a primitive character of the nepionic stagesuch as may be retained in various genera; and it is to be noted that Nanno (Middle Ordovician) is later even than the Canadian (Tremadocian) Piloceraswithout pre-septal cone and with the siphuncle either in contact with the ventral wall of the conch or subcentral. But the primitive Piloceras itself is preceded by Ozarkian forms some of which have wide marginal or sub- marginal siphuncles and a curved cup-like shape (Clarhoceras), while others are more elongated and have a narrower siphuncle (Ellesmereocera.s)or are fusiform, short and inflated (Eremoceras).They are all densiseptate (Fig. rz), often laterally comPressed, and the marginal siphuncles are holochoanitic, i.e. the prolongations 'soraropd eqt ur Sur.readdetsrg relcerego .^aauB Jo os€c rer{}ouu ,{lqeqord sl slI{J 'uer4rez1 'crlrueoqcoloq uerltr e8els errrlrurrrd oJor.rr€ selouep 1r aW uI tseel 1e sr pue d1.ruas sDnroqtqJ sE lng (('euoJ IBToJSIAeql Jo le^\erpqllm alalduroc orour er{l Jo acuenbesuoc rrr alcunqdrs oI{} Jo ezISoq} Jo uol}cnper eq} ulor; 3ur11ns -al'uorlnlossrp Jo ssecoJde ur r(ltcurlsrp se/v\ornlcnJls Jelncunqdrsopue oJlluo,, '(a1s.raog.,tq eqf (ltt'd'9o6r) uueuropend o1 Surproccy papueuresE,.'eepll -EJ?JopueudJ,, pue) ouprlereJolr4 dptrre; IeluaurepunJ oql Jo sturoJ elencre oI{1 'e8e 'sancoqtolJ Suoure snue8 8utlse;elur dlrelncrlred u sr uar1rvz1 reddg 1o '("{lS pue ssaurnq) pueltocs pue (dnorg ceqenQ uerpeue3) puelpunoJ^\oNl JO seuolseulT uetsau8etr4l 'razrettoq '1ott 'lla.{s egl Jo osoql rrer{} sad& ezrrlrtuud oJour e}?Jrpul op pelloc 'o7aun7{u.to? e saflnf.1 ((lrrepunqc leq.{aauros,,oq} pue asuaq.4ozo((sota?oll1.to,, ',(8o1oa8 lnJlqnop eql JO (0ggt) suorldr-rcsePs(preulnqs Jo s>leerq-atullleer8 eql
.(5o6r ,uuuruapang 'podoleqdec wo{ pardoc) re}sa{uuT deg .ragu luul8tro crletuttrurB -tslp ,f .r26r 'etrsraoCJailB (s8urlpg) xr.tt1d,$so,eJorua,Lg't-B '(lz6r) frocpll'sxsuauosqo,t sota?oatatu 'cq 'ftt -tiit7'.{ .(rz6r) a1s-r-og 'uaqcs sbtatoantusallg'a-t '(rz6r) e}sreorr 'l1t1opat1ot1soraro7.tolJ t. 'epodoleqda3 't-ozt 'Brg 1SoOi1uuuruepeng.rar;e (a4ruy3) q1atlcutoz-uoJltau.sDfiro1,tnlJ'u uurryezg
Offi'll/ q jY/"\\
egl sleeds (1ce;u1 Jo ouo sB u?rcr^opro eql pus uErpBuBJeql uoa,^aleqIBAreluI Jo ,alsreog 'eloqe uerorlopro orll;o 1e{} uro{ dlqereprsuocre5lp }nq eunuJ (uerpeue3 -re,l.o1) uerropuurarl er{} q}l^a eloq./v\el{t uo ear8e (lueserd eq} o} dn paqrrcsap dlerenbepeur dran q8noqrle) spaq uarryezo ur tsrxe o] pIBSspodoleqdoc snoreurnu 'esrlBer eql lBr{1 U e{B} ,(eru ervr eln{^\uBetu }ng s1sr3o1oa3gsqSug dueul ueql uercr^opJo ot{} pus UBIJqIIIBJ eI{} uee/vUeqeJolu JBJJoJ ulooJ SI eJeIItrpu8 e}sJncc8 'dleleunlroJufl uro{ rey le.{ sB sI seere }ueraglp Jo s}Isodap eqf Jo uo4€le.l.roc 'sofi?oxll'to ou gEnoqrle .readdelsrg osls sauoJoqtrro3uo1 'sl{lBarls eJer{/r\suorl€ruJoJ 'uerpeue3 '.req3rq lxeu aq} ur dluo pedolanep eJe esoql -oqdrsopuo ou oru eroql 1nq eldes Surpecerd eql otcrleuad slauuny leldes eql Jo $l opodopLl{a3 aqt {o uoqtnloaaaLIJ 452 L. F. Speru early stages' and in my opinion the filling of the siphuncle with endosipho-sheaths is a secondary feature as much as the apical cone of lr{anno(Fig. r3). The early stages of a Tremadocian Cyrtendoceras or byriorrrina already essentially resemble the shell apex of the living l{autilus pompil'ius. From this tim! onwards the nautilid stock is found continuously. We can, with Dacqud (tgzt), recognise only a very slow progress during the Palaeozoictowards greater it uoi.riiorr, but I do not believe that there is any difference between the mlde of life of the recent forms and that of their "swimming ancestors." The shell, apart from its function as a protection for the soft parts, is clearly a swimming organ f and we have already seen that bilateral symmetry is common to all young nautiloids. As with other characters I consider it probable that the coiling was first acquired in the young and not in the adult; the young of the ancestral forms with arcuate shells
Fig. 13. Straight Nautiloidea. a, Nanno belemnitiforrne's_(Holm), Ordovician, with pre-septal apical gone (l), wide marginal siohuncle (B), and camerae (C). After Holm. b-f , various Ordovician to Devonian orthocones, showing asymmetrical colour markings. After Foerste, slightly "nf"rl;a. that found themselves provided with considerable curvature may be assumed to have led a more freely swimming existencethan their less curved kindred; but all the intermediate types co-existed from the earliest period onward and the straight and late Orthocera.r,often with colour-markings (Fig. r3) as in other shallow-water Mollusca, is as much an adaptive development of the .o^*o1 ancestor as is the regularly or irregularly coiled nautilid shell. The small and incompletely known Cyrtocerascambria Walcott (r9r3, p. 98, VII fig.. ll 4, +a-c) from the Upper Cambrian of China, also appar.nity ,ir.-bi.. Canadian forms; and since all the Ozarkian nautiloids are holochoarrit.r, there seemsto be no reason for Teichert's (r929) assumption that it is the ancestralform of the " cyrtochoanites," i.e. the polyphyletic actinoceratoidsof the table on p. 455. No coiled nautilid comparable to Shumard's Lituites complanala seemsto have been rediscovered in association with the primitive curved and cup-shaped forms cited above. But if Hyatt were right in considering a loosenedbody Lhamber or free outer (..solrueoqcoql;O,, eqlJo elrtrelrreserdeJalrllurlJd E pue podoleqdoc IBaJe sI lI IBII} '9z6r) 'peur8eurl uorurdo Jo sl (Sg'd Slo.tnapurqcg eq plnoc let{},,spodo1eqdec,, SurculnuoJun lsour eql aJBdaqr rnq'souoc elnulur eseql Jo suoulcads 3o spoJPunq .f,ueu ql1,t\ peroloc ere runesntr\l qslllrg eql w DllaLft,toqloAtlll^d {cor Jo sqBIS 'lz6r egl ,,'podoreld,, e.f,1.returoJosle'(8'd ees)n11a,taqDS snuaE s,sEurlpg 'acue;eadde "pelJ rllliA lecrluepr .,tlqrssodsr }r pue 1s.rgrlaqt e{Bur osle fseqrlofH] spod -o.rold crdocso.rclturlJlr{/v\ uI ?Iuoq}sg Jo.,f,nlJ etr1fl,, pellsJ-os eq} tuol; PaqIJJSep 'auros lsJU se,t,rollaqlnqlol ,,{q pesse.rd sr urelc slq} qJII{.l,r rI}L{a ecueJnsseeI{} 'podoleqdal segrlsnl erueprle er{} rer{}eqrrt';ele.noq 'peuot}sanb eq deu 11 }seIIJBa eql eq ol parulelcuaeq sBI{(888r ''g '}pttul{rs) vilaUl,rcqloA ur.llrqluleJro.^AoT egl
.V'ITTHJAOq'IOA CIOdO'IVHdgC CgSOddNS gHJ'IA er{rJo ,$y'qrsneld eqtdq pue'e1c.(c pcrleqtod ^r;'!::::#:#;""":il:iil;l'Jliii; ,,ssau1g8reJls,,aqlJo Eurssa;lseqr dq peuolsrp ueoq aculs seq erntrud crlaua8 eql 'o8e 1nq s;ear{ .,tueuru.taou>l se,{A, }BI{.{a uo eJueAPsel}}ll sluasardal slr{l IIB ,&\oN 'elcunqdrs papeol e pe;rnbar releu o8els pa1eu d1.reeerll reUB oJII Jo oPoru luereglP B ol se^lesureqlSuqdepe 'eeprp1ne51dpea eql'a'x 'e.rn1e.r.rnc;elea;8qll^\ esogt dllercedse '(slooqsgo ,seueloduroluoJ olrlce aJour eql rnq eleuoqdlsoullJe trer{l pue) spnerac -oguo eql pu? sprlErocopua aql qroq Jo srolsacuBeI{} a9 ot perePlsuoc eq ,tetu leql 'uollecglpour (spqerecoererusalla)selruuoqcoloq dpue eql sr lJ ,t-repuocesB d1me1c ''c1a 'tusltue8r8 'qlro; sr 'sprlerecopue Jolel eql pesrJelceJer{c}Br{l qlllrr peulquoc 'slauuny 'pacnpord os pue sr{leeqs-oqdrsopua;o pe8relua ,{1leo.r8Jo uolteturoJ eql alcunqdrs eql pue pourroJ ero/r\sraqtuerlJ rr€ cESIBJecsIA or{} Jo uollel}ueJagrp egr .{q ,dnc 'psso; 'a'? pue uedo uB e{rl padeqs se,r B se poArasard aq o1 ,{1o4r1lloqs tsrg aI{} 'auoc '11",{. snoereclec rl}ri\\ 'eddleqcre Jruoqluaq .{1r:eurrd aqt leql paunsse sI }I lecrde aql o1 ro r{cuoJolo;d eql o} rulnurs urroJ ssaleldes pu? ssolJeqtuel{cetuos uI ur8rro uoururor B purl dlquqord 'epodorald luarJue oql pue sanln?Dtual'epodortseC 'qcuocolo-rd eqt dleureu eql e^Er1r{rpl.^a spuH raqlo Jo sturoJ pore^oc-llaqs eql pue epodoleqda3 Jo sr.uroJalcrper aqr IIB ter{t-uollelnlrducer Jo }uePuadapur a}rnb 'dd 'f6gr) -(r-ogt pe.{g Jo ^\orl eq} o} uor}rsoddo el}rll eq ilI}s III^^'erel{.1, '([zt'3rg aas)euoctlndec goqs ro dnc uado lzrlsecue oql ol auocop.{c TBIILuIse ro sDnropd tilory dels ? lnq eq ppo.&\ tr 'lou ro sr.uroJlq8rerls pue pe^rnc aql qll.t.r.aprs ,(q epIS polslxe .,(puarp 'esec 'aJuelsrxe sruJoJpalroc Jer{}eq.a ,(ue u1 Jo sopotu }uaro3lp lil}s tueserdar asrnoc 'raproq '')1e 'sotaloqxolJ 'soncotpttldg 'aldurexe 3o qlnotu pelcrJtrsuocqlr/y\ uoryo 'u1 'sprlrnlrl ro; suorleururral elger€druoc e>p1 lcoJradurr er{l Jo otuos 3o sernlradz 'pessnosrp peuosool eqJ ereq sed,{} }q8rerls eq} Jo auros Jo reql ol olqereduoc 'Surruturrvrs-ear;'euocrltlneu 'a'? oJII Jo apotu e f,q papeeccns se/y\e8els ,t1.leeaql 't1npe 'Eurpoc eql uI oJIIJo aporu lelceds ? ot uoq?1depuuB eq ol U raPlsuoc I 1nq erlrsse:Eordur e8els e se sarynlaTuodnpo{ool e^Eq srer{lo 'ed,tr elereue8ep e dpeerle eq plno^\ pll1nlll uar4rez1 sqt Eurpocun ;o SuruurEeq egr tueserdar ol lrotlll\ tsn upodopq{a3 aqt to uogn7oaaaIIJ 454 L. F. Spern I disagree entirely and rvith Pompeckj (1928, p. 8il I question Schindewolf,s deductions as to the phylogeny of the earliest nautiloids. The little cones are so variable and so irregular, and their preservation is so different from that of the later and larger cephaLpods with hyclrostaticshells, that rvith Krause atld Giirich (1928, p. 83) I cannot accept them as cephalopods. Hyatt (r9oo, p. ,,flaring', 5 r6), ascribing to Volborthet\ not only conical septa but a living chamber, in any case,had quite a clifferent opinion, fo, 1o regarded it as one of a highly specialised family Ascoceratidae,of the sub-order Mixochoanites, animals adapted to a peculiar mode of life in the adult and certainly without the slightest affinity with, or even resemblance to, Volborthella. This was recognised by Flerste (tgzs, p. +), who stated that Volborthel/ashould be associatedwith Salterilla, with- out, however' expressing any opinion as to its cephalopod (or'Voiborth)ila pteropod) nature. Karpinsky - (r9o3) figured a number of speclrn.rs of of varying shapes, but all his illustrations are greatly enlarged, and those who do not know the actual fossils may easily take certain features, as, for example, his diagrammatic drarving of the supposed cast of an air chamber (Fig. 6, enlarged > -- qcFla\ qll^{ selrEroduretuoc palroc pu? po^rnc asoql o} parlrB}tB eq }sn(u spru?lla^of ueluolee pue UBIcI^oprO aqt a{rl slloqs tq8rerls ^{prepuoces}?q} reelJ sl }I 'spr}Brec -opue 's.raq pelleqs-lq8rcr1s orll Jo luaurdolelap runrurxrur;o por:ed ogl tB sn{t pue -urBt{c 's11eqs JIB so-lsBc r{}r/K serur}ouros pelrocun 01 asrJ aneS pue uor}ceJrp drer\e 'Surpoc trsotulBuI posllelcads etuecaq deql pue sedeqs Jo qllea,{e}ea:3 e luesa;d 'uetcopeurorl eI{} ur dpee-r1epunoJ 'eeur1rn1r1pue 'auur}rlorlJorl 'eeur}elaJdqdrzg 'saEels solltueJ-qns eql Jo sruroJ pelror orll oslv elerpeurrelul IIB pug or tcadxa plno.t\ ouo sursrue8JoJBIngn] oseql ur qilro-r8 leurrou Jo llnser erll se lsauoco.rd8 puB sauocol;r{c uaa,/Y\}oqeurl Surpr^rp IBrnlsu ou sr arar{} }BrIl peppB eq plnoqs 1I u€IxIorJ:addn [er.rqtuec,}nr";T^lr,], g j:.Ifr;g$i iI r5c suJaf,oaJoLusalla :";1,";:::'ili$! ,/'suJaeo>IJBIJ^,:1:1-l^ / t) SEJEC f{Ar"a suraco'Id uBrpBuE),r*o"l | g I * I I i' Tr i .,",p"uBJerpprtrN ! H r--f- P Jo lF I i -- .tE uBrpBuBJraddnJ 5 I 7 6 ? i )."'r{ n iE Eru F IPN I ,,.i$ i--.8 li! ",,;,"1]F ",,/ - e1cgra.,so1l f_? | , 6' I -j- ,1, raoaqJ "eg 'Daprclq?ta^I[1.toa aqg 'I elqe; 'pallrtuo e.resdnor8 talleus or{} Jo duetu 'ua.Lr8 ssauJeelcJo o{es aI{} roJ 1nq ,tou sr drqsuor}Blerrelul s1{} ,!\or{s ol aueqcs 'so,tnoq,tulJ '(sprleracopd rulnq€} v pue sD,raroanutsallilSurpnlcur pue) sprlerecopua oqt'd't'salrueogcoloq a^rlruurd eql uro{ pa^rrep ere setrueor.Iroguoeq} teq} (gz6t) 'plaqdn uosspaor,I, qll^a ao.r8eI rnq eq louuec srrorsrlrp [BrJSruEeser{} ler{l ^\oqs IIL&\ 'salrueorlool.r,(c lQnop ou solJalocsrpoJnlnC Jo salrueor{coquoou apnlJur daqt teql 'se.rnlJllJls pue JulnJunl{drsopua lnoq}r.,!\ 'salrueoqcolorl oJe spodoleqdec lsarpea 'ueq} '3uuou31 eql ter{r punoJ sr y QtyanilDs rc) n11aqtnqloA InJ}qnop eq} .VCIOdO'IYHdSJ 'IIA gHJ, -{O ANgCO'IAHd gHJ 'lselord srql asreJo1 d;esseceusr 1r 'rolsecue podoleqder (,,crlrueoqrorluo ,,) a,rrlrurr.rdeqr se Dllalfi,toq1ol peldecce .(1a1lugapo^er{ (626r) uoqcrea pue (rz6r) gnbceq e>lrlsrorllo pue roqlne srql ecurs lnq 'sdno.r8 I?crlzruolqordol seureu(( I€uorsrloJd,, a.l,r8o1 lduatle (626r) s.nEqBJOse ernleurerd sB surees,,luaru,tequre rddrsslssl6 oql Jo rllnos aql o] sursuqcrueeco ur pa1eurEr.ro,, spodorlse8pue spodoleqdecleql uorldunsse (toS 'd 'r 16r) s.rlrrrlfl 'Dllantlos pue 'ueql 'drussecau DnarynoqloAIo ornluu eqt Eurp-re8e.rpurur uado ue daa4 o1 sr 11 'rolserue podoleqdec enr1 er{} Jo luepuedepur ,{pre}rec }sorule se/v\ 'uorlelnqel ll lnq ro uorleldes le {co}s podo.reld a.r,rlnurrdeuros 3o ldruape elruoqu SS+ Dpodopq{a3ary {o uo.r.ru1oaaaqJ +56 L. F. Spnrn all the other characters,including the siphuncle, show them to be related; but as already mentioned a classification of these cephalopods into distinct sub-orders by the structure of the siphuncle alone must be unnatural. The ammonoi d Cyrto- clymenia and the Tertiary nautiloid Aturia, with dorsal siphuncles, developed long siphonal funnels quite independently and have no affinity whatever with the endo- ceratids. Conversely some endoceratids like Protocyclocerasmay become ortho- choanoidal without being distinguishable specifically from the typical holochoanoidal forms. Only close association in date of the various forms and consideration of all their characters, even microscopic, will eventually lead to a more natural classi- fication, but it will not be a return to a system based on coiling or whorl shape, as might be wrongly suggested by the accompanying table I or the writer's QgzT a, b) sub-division of the Mesozoic nautili. In r 894, Hyatt (p. :6S) admitted that " the whole seriesof forms from the straight to the nautilian, were present in the earliest period." But elsewhere he assertedthat Diphragmida and Endoceratida slightly preceded the nautilian forms or at least that their earlier existencecould be deduced by " noting how the number of coiled shells diminished as the Palaeozoic was followed backwards, especially when the lost records of Protozoic time were taken into account" (p. 166). Later (r9oo, p. 533) Hyatt again attempted to prove statistically that in the earlier formations, orthocones, together with their almost invariably associatedcyrtocones, predominated, and he rvent on to say that " the Permian had but one surviving family of orthocones and four of the coiled groups; in the Trias the ratio was one to six, and in the Jurassic coiled forms alone persisted. Thus a slowly working tendency was apparent, leading to the production of more and more closely coiled cones and the elimination of straight and slightly curved forms." Now it is a matter of common observation that the straight shells are most abundant still in the Upper Palaeozoic,but when even Blake (t9gz, p. 285) who had monographed the early British cephalopods, uncritically repeated Hyatt's dictum that in the Palaeozoicperiods we reached in successionthe orthoceratitic, the cyrto- ceratitic, the gyroceratitic, and the close-coiled nautiloid stages, general palaeonto- logists like Dollo Qgzz) may be forgiven for accepting this as a true evolutionary series. It will be seen, however, that there is neither gradual elimination of the straight forms which indeed are far more numerous than coiled nautiloids through- out the Permian and Triassic, nor is there any successive replacement of these straight shells in time by cyrtocones, gyrocones and nautilicones. Otherwise Hyatt's remarks only show that the straight type of nautiloid shell co-existed with the truly nautilian forms from the Ozarkian onwards; and if one can recognise replacement at all in this connection one should look for it in the Dibranchiata, like the Triassic Atractites, Aulacoceras and the host of Jurassic and Cretaceous Belemnitidae that continue the " straight " development. Since Quenstedt's days such successful recent cephalopods as cuttle fishes and squids have been universally considered to have descended from the belemnitids; and I agreewith Hyatt (t894, p. 352) and von Biilow (t9t5, p.4) that belemnitids arose from the Orthocerasstock by inclusion (and by resorption) of the shell within ur (soraroqlq) ploll}n?u (eturqcuerqerlel '(1qe Ilar{s aq} Jo uolsnlcul Jo acuenbasuoJ sI -unsoJd pue) fg8rerls B tuo{ asorc sotell{cuerqlp }seIIrBeeq} }Br{} Pe^aIIeg lI .(ztfu,uosqog) orncsqo dran ere sndopoaorydrlll\\ srePro-gns ]uereJIP lyls (eldtuexa perre,r ,t1eue.r1xeuB er, sPodolco eql eql Jo suorlelorrelur;ql pue dnor3 JoJ : pelerleq .(lleJaua8Sr se elqlssodtut oS lou SI lcols olluourrue ue Jo sluePuaJsop dep-luesard eqt euros lsBel 1B]Etll ,\A'eI^eql ssal-llaqs-:d1i,rge eql luesa;da-rselerqcusrqrp Jo qclq'u) sary1{ntg 1.,g lselq8qs eql tou eABq(relncrged ur palrc uuuurulalg 'sptoltlneu B pu€ sn{opoan1od e1llulroJ snoocz}arJ B }BI{} PUBsplouotuutu uea'^Aleq 'lqnop '@z6r) .ftiuge osolr agr Bururrr,ror prESueaq seq leq] IIB rage ou eAeI{ 1 ']cut]slP 'eeptordeg 'eaproutuolag) p"1.r33.r. JOB,NIse euocaq Peq (eeprogfneJ Pu€ TISSBITIeql sdeq'rad)ed'{1 .r1ro1, pod"ctp ledrcurrd tttqf eql oroJaq (sprlurecorelne poOnttp ,(1-rea-ueulo{ pe^Irep uoeq e^Er{,,(ewspodolco eq} pue eroJeq petrcaieruaoq SBq salruoluure oI{1 qtrI.,tasprlneuo8J? eI{} Jo uol}cauuof, alqlssod E Jo ^\aIA S(uueur ,esrnoc .snoocelarJ €aplouorutuv oq} ecuerEadde -ulols ;g er{} ;o do1 eq} }E Jo -srp uoppns eqt qlr.,lAuorlreuuoc ur uorlsaS8ns B a>lelu o1 dpo dlrunlroddo srql .^&euou roJo uBc a)Fl puB slBrqruBrqlc eql Jo uorlnlo^e er{} SurpJe8er slcBJ I .VJVIHJNVUgIC gHJ'IIIA t4 uEIJgluBJ uErcopBtueJI usrcraoPJo uelrnlrs o salIJl3Bqoqo-I sEJacoJAc r-t it uBtuo^ec[ uruaufl3- seicog,{3 f B>t 3 D) snoJaJIuoqrEJ o d u 0- o !) o- o uEItuJad o D) z -/1 D' cISSBIJJ ssresopqBqu/ c tD | o ) i (D o. I ctsse:nf | A) J o u "nrertrnnv/ I A -/1 I I il snoas€lal3 sarllncugt/ I o I D) l-L I I I I d:eruaa I ,/\- I v /t. (i) snlrln?N tl\ BlsItlsuEJqeJlaJ BlBrqcusJqIO luasau 'opodo1nqdaS .II aqt {o uo4ryo$a aqJ OIqBI 'suorlEloJJ0lur oseql el?Jlsnlll ol stdurelle epodoleqde3 eql Jo aa:1 lecrSoleaue88ur.,rno11o5 aq; 'selurl euecolN ecurslseol lu uorlelosr peqsrn8utlstpunut para8ull ser{snlqnoN snue8'papoc'e18uts 'ucsn11otr41 oql tslr{/r\ Jno Jo 1sa3:e1Pu€ peslue8ro .,{1qBIq}sotu oq} w Sutgsunog III}s ,sproltneu 'elluBru lqErertrseql Jo sluBpuocsapJo lsoq B e^BI{snql e1!\ er{}Jo sPIoJeq} LS' Dpodoluq{a3 aqt {o uo1'ru1oaaa?'[J t 458 L. F. SpnrH by the mantle, and this processwas not gradual considering the sudden appearance of the aulacoceratidsand the extraordinarily rapid rise of the Belemnoidea. It is not probable that such a processrecurred in the history of the Cephalopoda, but even if it did it would probably not have proceeded on exactly the samelin... Thus it does not follow that a resistant phragmocone, with or without solid guard, would again have been formed. If inclusion by the mantle and consequentresorp- tion of a thin and fragile baculite shell be envisaged,the early initial coiling might conceivablybe held to be an obstacle,although it is not certain that, for.*u-pl., ih. Cenomanian Cyrtocheilu.s(an early baculite) had a coiled beginning like some Senonian speciesdescribed from American deposits, and in any casethe early coil is microscopic even in many Albian hamitids, unlike the coiled phragmocone of a Spirulirostra. However, there need not have been absorption but mere discarding of the shell. It is known that some species of Orthoceras and other nautiloids shed all or part of the earher, camerate,portion and sealedoff the posterior end by secondarydeposits. This was a first step towards the suppressionof the shell, and in uny .u.. it was no longer a hydrostatic apparatus. The ascoceratidseven formed two entirely different types of shell in their ontogeny. The origin of the belemnites is quite independent of these early attempts, but it seems to me conceivable that in any heteromorph or uncoiling stock the shell may have been shed in the young in order to enabie the animal to move about more freely. I do not consider the slight complication of the septal edge to be decisive evidence against this view. There *u. ,ro orthogenetic tendency in the ammonoids to complicate the suture line, throughout the Meso zoic, as has been asserted; when the whorl section of a baculite or hamite was circular, the septal edge generally simplified and the hold of the animal upon its shell was greatly reduced. The complex suture line was never uselessin the ammonoids any more than the guard of the belemnites; and the suggestionthat they merely reflect an ingenious way of depositing superfluous calcium carbonate (Lang, r9r)t p. 6+) seemsto me quite untenable. Baculitids were the dominant ammonoid stock at the end of the Cretaceous. There are many baculite limestones as crowded with these straight shells as any belemnite " battle field," especiallyin the Maestrichtian, the highest ammonitiferous formation of the Mesozoic. But,the maximum in size was attained already in the Campanian. True ammonites stili occurred together with the highest baculites and a few other heteromorphs; and Indocerasbaluchistanense, the lateJ known ammonite species,with seventy-five lobes and saddles in its suture line, shows no " senile" characters, but recalls rather the acme of ammonite specialisation in the Upper Trias. But these ammonites had become very scar.., ull the same, in computiro., with the straight forms, and the increasing competition by the naked d.cupod. -ay well have prompted some admittedly very adaptable heteromorph stock to attempt a shell-less mode of life. The hydrostatic portion of a large Eaculites grandis,'of course' is still nearly half of the total shell, but in similar rrnull., speciesiI *uy have been reduced or it may have been shed at an early stage. In u.ty case no passage forms are known between Orthocerqs and Atractites or Aulacoceras.We know now 'slsa38ns snoeueSouroqerour Seureucueue8 Jo uollecqdrtlnru eql u€ql sdno.lS 'eaplolllnpNi 'eaprouoruuy '6 puz cr1e1.(qdouorueJe/y\ eql a>11 eqJ Jv! eJEqloq 'alq"lsun sEA\'ranervroq '.{cgm 'elcunqdrs eq} uoI}ISod eqf u1 }dacxa seuoJIII}nEu ,t1snor.ro1ou Jo '8 ssel ro erour aql aTII dlprluesse era,^aseltletuo8 ]sellree oql 'alcunqdrs "j"tojt"durl luur8-reu 'L B r{lu!\ sn,taroqt,touB .(leJalu st (sa7a7o.ta?oqtto;oru.{uou,(s e) ((salx'tlrl)g,) .(.rfr ,so.racocsy,sontoanntq4) suorleldepe lulceds ro seuoJ '9 -llllneu pellocun ore./v\(seuocoqtro oulos pue) seuocolrdcpue sauoJo'r'{8fsolq 'S .peqs Jeleu se/rrpuc SnoeJeclccsr{e.,vr1e SB,4A splolllneu uI qcuocolo'rd eqa 'uEI)oPeluoJI eqt uI dpte.rle palslxo snclllqurn a1e-ro;radurlssal ro arour Utr^.::i::"H*?,rI,"* 'ouoco}rdc eq} ruo{ uz luaseJder lou op Surpoc errrssa.rSo-rdgo sa3?1ser{I e.Lr}nur"rd '1srg 'L ,(lfuapuadepurpadole^eP (seuocorqdo 1z) sauoclllln"u PUBsouocol{lro ' '(auoc (:zg+'d 'urnpuepPv aes1ng) ro) gcuoc 1e1des-erd (auoc ou pue (crlruzoqcoloq) alcunqdrs PePeolun PuE oPL\A'I{lL^a lecrde leur8reur 'z Itl.rdnr ro auocol.rr(c ,(11erare1rq€ se,^a podopgdac Ierlserue eqJ leculeruuds '(podo-re1d rc) ollalftnqloA 'r pellec-os -ro podo.reld t ) podoleqdec € tou sI (n77an77og : s./v\olloJse peslreururns (d1runlq ootr aqa ler{^\euos sdeq-radq8noqr) ,,(gar.rqaq ,(eu le poAIJJEsuolsnlcuoc ledrcur-ld ,AUV'\II\INS 'XI .suorl€urroJ uE ,(q pacuequs sI edoJng lBuorlrsuBJl,(11ea-r Jo ocuesqBl€luePrcJe ur seun?J eulreur ,Ctnifi"J, .{1.reepue snoers}erJ a}EI eq} uI ecuere5rp }ua'redde eqt 'sprlruuraleq eql se ecueraglP el]]II se esrnor Jo lnq dq sz,IaroLll'toJo luetuecelda-r ornleu duouore el{l epBrue^Bq plno/v\spllllnceq Jo Ileqs aql Jo ecue-readdeslPeql ;o uI 'ouII] euIBSeql lnoq? pa-readdeslPlsotule osl? rellel aql [q'^asnollqo eq plnolr ]I ,salrurueleq Surrrr.nJns.l\oJ lwl eql uBtll aIIJIA eJour aQ of PaurnssBeJe'{\ sluepueJsaP 'spllllnczq Suro8 e9 ol u'^aou>lselluoruul€ enrl ssal-lleqs rlaql JI oql eroJeq u/!\oP 'snoecelerJ ere^\ suol}IPuo3 'ssaco'rdsrq} qll^a er{l Jo Pua erl} }3 }uaro5tlP d1e-ll}ue o} '.rerre,tit'oq'etu 01 d-russacauulees }ou Saop}I Jo uollllede.r luenbel; ? a}elndr}s .oler{spaurerS-aug ,{ren u ur suorssa:drutpen-rase.ld-llaa flSurpeacxa sregurnu ,ila,rocsrpaql [q dlqrssodldecxe'll"q. ap8er; 't1aua'r1xcPUE repuals Jo Jo '>1co1s irqlo,rl 'priord eq(so,ta?tlDw7uer^oll€J eqt'3'a reIIrBeuE uI uouauouegd 'llor{s dJlporu ,{1a-lau selres a'ttssa'r8 JEIrurs B Jo ecueJrnJJo eI{1plnoo roNI eq} }Brll -oid qft^ uele potertsuotueP aq louuec s{ull r{ons i re.{e1dpeed e Jo ro srequeqc 'salcsnru eI{} uol}cnPer rre Jo uolleluroJ ou ,(11eugse.^a ereq] Illun llaqs Jo lenPerts qlf^ ,(ir .d ,6o-6r) .(q pe8esrlue sBsruroJ e8essedou ere eral{} }Bq} Sulsl-rdrns "q;f'pluurBl{ eAISSerts lsBel eql uI lou sI 1I rel{}o ro olllnceq B ul IIsI{s eql Jo uol}€rglpoul -ord SE .selruuraloq eql ol sD,LaJoUt.rOTJ,ro' SuIJoJa3essed Jo SeIJeSalalduroc e " ^aau Sulees uo lsrsur ol alpl sB aq plno/K 1l lBr{} puB suor}Etl?ssE peJueddesad,tr lBtll 65t upodoluqdaSaqt {o uognloaaaUJ 46o L. F. Spnrn ro. Goniatites with unstable siphuncle gave rise to the clymenids which (like the holochoanitic nautiloid Aturia) died out compretely. rr. Ammonites are the descendantsof goniatites, not of clymenids. 12. Gyroceratites (: " Mimoceras") and Lobobactrites are derivatives of gonia- tites. 13. No seriesfrom straight to coiled are known but only such as go in the reverse direction, in Nautiloidea as in Ammonoidea. r+. The position of the siphuncle in the nepionic stage in ammonites was extremely variable and has no phylogenetic significance. r5. Palingenetic methods are discredited as the result of the writer's practical experience. Hyatt's and his followers' evolutionary seriesbeing constructed on the principle of recapitulation cannot, of course,be used in support"of such palingenesis. t6. All charactersmust be used as a basis for classificationand all are variable. Reliance on siphuncular structure only in nautiloids leads to unnatural groupings as much as the undue stressing of the suture line in Ammonoidea. 17. The possibility of Baculiles having left shell-lessdescendants is discussed. REFERENCES. BAnneNnr-, (r8Sg. Ascoceras,prototype J. " des Nautilides." Btill. Soc.96ol.. France (z),2, 16o. BelH-nn, F. A' (r9rr). Guide to the Fossil ftruertebrate Animais in ihe Ar;i;tn Museunt. znd ed. London. BLaxe, F. (l8gz). J. "The evolution and classification of the Cephalopoda, an account of recent advances." Proc. Geol. Assoc. !2. BneN-co,W. (r879-8o). "Beitrdge zur Entwicklungsgeschichte der fossilen Cephalopoden. I, II.,, P ala eont ogr ap hi ca, 26-27 . Bulow, E. v.,(r9r5). "Orthoceras und Belemnitiden der Trias von Timor." pal. Timor. g,7. CLetrx, Ts' H. (tsz+). "The palaeontology 'Butt. of the Beekmantown Series at Levis, euebec.,; Amer. Pal.7O,4t. Ctenxr,-Jr-M. (r8sg). "Ih" Naoles-Fauna (Fauna w. Manticoceras intumescens)in Western New York." N.Y. State Mus. 5oth Ann. Rept. (t8g6),2. CoRnrNs, C. W' Ogz+). " Der Odershauseifutt im-oberen Mitteldevon. Ein Beitrag zur Deutung fossilreicher Kalklinsen in Tonschiefern." N. Jahrb. f. Min. etc., Beil. Ba. +s. Dacgu6, E. (r9zr). Verg-leichendebiologische Formenkunde der fossilen'nirj)ri m"rr. Berlin. Davtrs, A. M. (rgzo). An fntroduction to palaeontology. London. DrxcxueNN, A' (r9oo)' "Goniatiten imObersilur des Steinhornes bei Schcinau im Kellerwalde.,, Jahrb. Preuss.geol. L.A.2O (r899), r95. Dorto, L. " Qgzz). Les Cdphalopodes d6ioul6s et l'irrdversibilitd de l'6voluti on.,, Bij6r. Dierktmde, 22. ErcneNsEnc, (rq:r). W. "Die Schichtfolge des Harzburg-Andreasberger Sattelzuges.,' 1,r. Min. etc., Beil. Bd. 65 (B). Jahrb.f. FoEnstr, A' F. (r893)' " Fossils of the Clinton Group in Ohio and Indian a.', Rept. Geol. Suru. Ohio, 7. - (tgzr). "Notes on Arctic Ordovician and Silurian Cephalopod,s." Btill. Denison Unia. rg. - (t'129. " Notes on Cephalopod gerrera: chiefly coiled Sllurian fo.ms.i Buu. Denison (Jnia. 2!.- - (r93o). " Color patterns of fossil Cephalopods, etc." Contrib. Mus. pal. (Jnizt.nfbng"i, s,Z. Foono, A. H. and Cnrcx, G. (t8sz). C. eatalogue of the Fossil crpna"p"i"'in the British Mttseum (Nat. Hist.), pt. 3. Fnncn, (rgoz). F. "ueber devonische Ammoneen.,, Beitr. Geol. pal. Ost._(Jng. 14. Gnan-au, A. W. (rszg). " Terms for the shell-elements in the Holochoanites." .B'utt.Geol. Soc.China 8.2.^Jve'v'ee"u' GnaNrlraN,F.(r9rr)' "LeSiphondesAmmonitesetdesBdlemnites." Bull.soc.gdol.France(4), 1O (r9ro). 'og 'sac 'pag 'L\rslna(I 'z '(gz6r) 'v ',Nanrr{vuHcs (('suralqord-uelrlBreJ sap Sunso-I er(L, 'Otr.((leEreos)'Iod'paC'nlJsttoi '(5z6r) 'nl '.r.ornrucg ..'uerpnlsuelruoLuruv,, 'Qz6t) 'V'7 '4oa7'ssnat4 'qnlDd '(5z6r) '11 'rcrltucg g, (('spu€F{cslna6l uelrleruoC ueqcsruoqrcr arq,, 'z'ge'(L)'qs,tara4 'tg 'tcg 'dtu1 'qDJV'ru?W '(898r)'C'rarr'rrrcs (.'puBllsg ur €un€d eqcsrJgurE{ra}unat>l3aplueneu eure ra9O,, 't 'rtr'.tq?snaz 'f)d '(zt6r) ..'ueeuoururv Jap alqJrqosa8saruruelSrnz,, - 'g'lsuosapuD7'pa1'ssnatd'ng'zlts '(rt(rr) - ,,'ogdrg-ualluourtuvuap raqel),, 't' g' qts.ro{aqau!r srg '{'tt1tvta7 '(626r) ualsallg Jep elqJrqcsa8souure}S pun {I}sua1s,(g ;n7,, - ,,'uapodolegda3 'r 'ot '.{q?sltaz 'lod ..'vePoo -opqda3 uatsollg Jep alrlcrqcse8saruruetsarp pun 'ruqJs sxnuatDqap.toqloA re9g,, '(9z6r) -- '6? 'pg 'pag ''o1e 'u?W '{'qqDf,'N 'apuelforl ,,'I ueqcsrsqces uap pun uab 'ua1ue.rg.laqo '(lz6r)'H 'O 'c'ro,lnscxrrrJ;r^ -urJnqtlso ur surnJrozoaladsep sruluue; Jnz a8erlrag ,, 't-z' L'rutsso71'tltnloN'nt1'q.qof, (('uelrleruol Jep uorlusruu8.rg Jep etcund s.re8r-reurqcsaJaJgaur raqg ua8unlq3uqoeg,, '(rSgr) 'C 'uacusscrNvs 'zt, 'nu.V '?oS 'pa1 'Ipg '(rz6r) - ..'spodopqde3 e,.r.r1rurr-rdJo eJll Jo epour eql uo suollelrasgg,, 'ZgT'snry '(zr6t) apxs'A'N'ltng ,,'da1p4 >I^BTIoIAI atltJo seleqs rrrnlls re.^ao'IegJ,, - 'f rp4 '96'srt2y apls 'A'N 'ilng '(9o6r) - (('urseg ureldueq3 er{t Jo suorleurroJ f,zvrq3 pue u,^ao}ueur>loageq} Jo upodoluqdaJ,, 'Og'snry '(5o6r)'U'NNVrrsosng apls'A'N'IIng ,,'spodolugde3 a,,lr1rur.rdatuosJo ernlcnrlg,, 'uopuo-I 'I 'opoilotcg '11 'opodo1oqdaC '(zt,6t) 'C 'C 'nosaog ('an8o1ure3 I'g) ruaray ary {o qdo.t&ouo7y 'susd 'sBItV 'sanuouruV sap atqdo,tSottoyJ '(6Lgr) '6 'sax,ra11 't' 1,'Stnquapuotg t{tohl np 3un34q?xsq?n,eg .orepuosaql4w'sapuoltlJold uaUrsry?p -pnu sap aqatqcsa7lozonl?Cluapuatqp{s&unr.autatstao ??p ,taqlt ua?unz1:tnsn|u11 '(o69r) 'y 'g-ral.ag 'ge311n1g 'sellv 'otnd uaqcstE2mq?Ssap uatxuotutuva?CI '(g-tggt) '^ 'V 'C 'rcarsutn$ '48 'd '(9z6r) '(9z6r) 'g 'f 'I>rcaawo6 uo uorssncsrp Jloaepurqcs aas 'Ll,'ct"'paC'uxry '{'p1ouua3 '(Lo6r) .<'son?orylto uol ratuurc4s8uu;uy erp raqoff ,, - 'dD.td 'ssxil'sar,) 'uqgq'4 'ng 'z1r.g '(zo6r) '6 'vrgo4 ,,'u,letg'soncoq|tg 3un71ec reP .ratuuru>1s8uEJuv3Jp ra9o,, 'r 'g 'IDd 'pa1 '(9o6r) 'g 'cxrrrao5l 1('C'N)'qqV ..'asuauDlsxq?nf)qsD.raropuJ uo^ Funlelct.utug alq ,, 'euef 'aqcs{uatu1a ualasso{atTJ '(zz6r) 'y 'uav51 'g'tsuosq?xag'7oa3'4'U'puoqqv 'uets11u11 '(tl,gr) '.t 'g'sJlAostslol4l ,;r'I un a8:rqag SBCI,, '(sntr41-uatr41) ''pa '(tBgr)'g'g'uarssxNv'I gl !t6'ocuuo|utg otpaodo1c,tcug(('BOSnIIotr\l,, 'rg'sa0 'pa) 'qrsltQ(I 'z (('spuBl '(zt6r) 'r11 'acNv1 -qcslneppJoN sBr.I uaJelun rur uelruouruv lnu o1ndng uol uasorqrudg raqan,, 'Og'?ossv'pa1'?o,td '(6r6r) 'CI '11 'cxv.1 (('selruoLulueJo uortrnlo^eeqtr,, '89 'd '(gz6r) '(9z6r) 'g '4 'asnvuy uo uorssnosrp Jlo.4aepurqcseas 'z'L'tqlsyaZ'pd '(5z6r)'y'uacNrrsury (.'ueeprolrlneNuar.{csrp€rJl uB uaEunqcnsJelu{l,, '81 ,(S) 8,moqsnlV4 .sg 'ttg 'flutJ'poJV'ilng 'n11aqtnq1or1 '(to6r) 'y',L>rsxrauv;1 ,,'lplurqJs uelrqureJ a-rua8el rns eloN,, .ge8pnlg 'lJessrg 'uanuouttuv ,ep uorlosruoS,tgpun asxaozsuaqaTary ,raqn '(6o6r) 'g 'Nuof lern8nuul 'rg'sag'jba7't1tsptap'7 '(zo6r) 'g 'raxavf .,'uapodoleqde3 teuaqrolsa8sne esre.^asueqeTpun uorlusrue8rO erp raqn uesaql, 'tya.rrts 'pag'S'n'uotrN '(to6r) ..'srroeculeJJ ar{r Jo sa}rleJe3opnas4,, - --_ 'tog-zoS 'dd \ '(uurulsug) 'fi&olotuoao1o4 '(oo6r) - .,'upodoluqdeJ,, uorlrpe qsrlSug tsr yooqlxal s;enlz u1 \_ 'tlr'g,g'?oS 'sopqd'nruV '?otd do '(i6gt) (.'Jr.ISIJelcEJEqJpertnbce ue 3o dua8olf,tld,, - 'eLg 'Ir2,oux 'q?'quoJ 'uosqnus '(688t) (.'eEpIleIrV at{} Jo sISeuaC,, - 'ZZ'H'N 'JoS '?otd '(i-tggr) uolsog .;spodoleqda3 IISSoJJo EraueO,, - 'z 'T, 'H'N '?oS 'ruary uolsog (.'BtErqJuBJgBJlaJJepJo snocsnllour eq1 Jo dnor8 errlua oql ur '(498t) 'y 'rrv,rg asoql pue lunpr^rpur aql ur oJIIJo sa8etstuaregrp eql uoa.&\teqtusrlalyered eql uO,, 'sBlle puE 'gT '('g'X) 'lsuDsapuo7'pa?'ssnat1 '4'qqv lxoJ ,,'a8rrqa11 ueqcslulaq5 vx (run1otqa.tatsD.o) '(569l) 'g 'ruuavzroll -auavry pur. xuqtnq sngoqdaco7uu?Stpu uarqcrqcg) uo^eplellltrAl eraqo sB(.L, 'oz 'qqc 'qYJols 'uani 'loac '(969.) (.'sota?oxuolsgsoq uasladsF>lsuro,, - 'g '(res.{uy pue saruuq) 'qqv 'IDd '(S88t) '11 't,tt"roH -raqcsrrnlrsra8rura uorlusrueS.ro areuur erp Jaqf1 ,, ,,'uapodoluqde3 'e9'lsut) '7oa3'4'q'qqof, '(to6r) 'g 'saNuoq -sqx?ag ,,'uapodoleqda3 ;ap erua8o1.{q4pun atuaEotuo rnz,, 'gg 'd '(9z6r) '(gz6r) 'g 'ncruqg \\--\ rro uorssnrsrp JIo.^epurqcs ees '1,1,'tSoquoaolod '(tqgr) ',4A.'J 'raanrng ----- (;Jle'uaruew,t13 raqf1 ,, ryt upodolurlfu3 aqt {o uogn4oaaaLIJ 46. L. F. Spern ScHucnrnr, C. Qgz4). In Pirsson and Schuchert, Textbook of Geology, pt. rr. New york. sHuMAno, (1863). B. F. "Notice of some new and imperfecily-k"oi,Jr ir;rii; from the primordial Zone (Potsdam Sandstone and Calciferous Sand group; of Wisconsin and Missouri.', Trans. Acad. Sce.St Louis,2, t. s*rtrH,J.P.(1932). "LowerTriassicAmmonoidsofNorthAmerica." u.s.Geol.sura.,prof.paper, 167. phyrogenie Soeor-nw, D. (r9r4). skizzen zur der Goniatiten. warsaw. Spetu, L. F. (1919). "Notes on Ammonjtes.,, Geol. Mog. 56 (5 parts). - (rgzo). "Thg Ammonite siphuncle." Geol. Mag. iZ. --!'s"l-32). Monograph of the Amntonoidea of the bauh. I. Palaeontogr. Soc., vols. for rgzt-zg; II, vols. for r9zg, rg3o. " - (tszs). lJpper Albian Ammonoidea from Portuguese East-Africa ." Ann. Transaaal Mus. rL,3. - GgzT "On the classification of the Tertiary Nautili." Ann. Mag. --G-sz]b-szo).^"Revision9). Nat. Hist. (il,2O. of the Jurassic Cephalopod fauna of Kacih (Cutch).','ijarts I-VI. Pal. Indica, N.S. 9, z. - (10:: b). Review of J. P. Smith " Lower Triassic Ammonoids in North America. " pal. Zeit. _ 2, No. 28o9. SuLc, I. GSSz). "Report on the discovery of embryonal chambers of Orthocerata in the Hlubobepy Limestone." Trau. Inst. Giol. pat. Unia. Chartes (prague.t. TucHrnT, -C. Qgzg). .'-'Zur Systematik und Entwicklungsgeschichte der dltesten Cephalopoden.,, Zeitschr. f . Geschiebeforsch.5, 4. TnonossoN, (tgz6). G- T. "On the Middle and Upper Ordovician faunas of Northern Greenland. I. Cephalopoda." 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Gnmdztige der Palaeontologie,6th ed. (Broili). Munich. ADDENDUM. Since writing the above account I have had the privilege of cliscussingOzarkian Cephalopoda with Prof. E. O. Ulrich of Washington and it appears not only that the Diphragmida (or endoceratids with tabulae in the siphuncle) must be added to the earliest types listed on p. {JJ, but that there is a great wealth of new and undescribed genera in the Ozarkian, 'Lituites' although complanata(see p. 452) is of Canadian age.