Ser. XV. HIMALAYAN FOSSILS, Vol. IV. THE FAUNA OF THE SPITI SHALES. FASCICULUS 2. PAGES 183 TO 806 AND PLATES XIX TO XLVIIIA AND LXXV1I TO XC1. By Dr. VICTOR UHLIG, Professor of Geology in the University of Vienna. HIMALAYITES, Uhlig.1 species from the Spiti Shales :— Himalayites Seideli Oppel sp. ' ai Icutianus n. sp. 11 Schlagintwetti n. sp. i n. sp. indet. II Hollaridi n. sp. ventricosus n. sp. / II Stoliczkai n. sp. umbo Strachey- Blanf ord. II depressus n. sp. hyphasis Blanford sp. ' II n. sp. indet. ' II hoplitiformis n. sp. / All the species of Himalayites are characterised by a widely umbilicated shell con- sisting of rounded, frequently broadly depressed, and only slightly overlapping volutions. The mode of coiling, particularly that of H. Seideli, recalls the genus Lytoceras ; the umbilical wall of all the species is rounded and slopes down rather obliquely towards the umbilicus ; m the adolescent and full-grown stages the height of the volutions is in- variably less than their breadth. In the adolescent and adult stages the sculpture possesses a very characteristic feature : at about half the height of the flanks, individual ribs swell up into strong knobs from which originate bundles of three to five branch-ribs. Between each two successive tubercle-bearing ribs there are intercalated from one to three simple ribs. In the major- ity of forms main and branch-ribs are disposed radially and take a straight course ; it is only in isolated species that the ribs are slightly deflected forward or show a slight sigmoi- dal curvature. On the other hand, the branch-ribs exhibit a fan-like disposition, the anterior ribs of each bundle being deflected forward, whilst the posterior ones assume a radial direction or even a slight backward inclination. T^he ribs extend across the ventral face forming transverse or slightly arched, prominent ridges. Along t»he median line they are slightly, although usually only just perceptibly, reduced ; this reduction 1 Pagos 1 to 132 of Professor Uhlig's Memoir, originally written in German, have been translated into English by Mr. L. L. Belinfante. The English translation of the remainder is from a rough draft by Professor P. Briihl, carefully rovised and largely re-written by Mr. E. Vredenburg, B 146 HIMALAYAN FOSSILS. tIB, fun.ow existing on the innermost whorls. Now constitutes the last trace oi tne v bilical suture coalescc into a tubercle, or an and then two ribs proceed..ag ^ ^ ^ ^ ^^g tuberc!e. The tuberclcs intercalated rib show* a ten y rkablc for tbeir stoutDess and massiveness and increase rapidly in thickness and aie ^ ^ ig preserved) it can be seen that l^^t^to acute spines. They were probably not hollow, but' rrtr: ral)1t' two principal lateral lobes and three smaller auxiliary obes which latter rapid y S T size. The external auxiliary lobes ordered u, conjunction with three internal auxihaiy lobes constitute together one slight y depressed umbihcal lobe The lobes are slender ; the saddles are broader than the lobes and they are to a varying extent constricted by secondary lobes and lateral branchlets of lateral lobes. The first lateral lobe is nearly as long as, or only a little shorter than, the external lobe; the second lateral lobe is much shorter and usually disposed obliquely. The umbilical lobe is situated at about the same level as the second lateral. The antisiphonal lobe is as long as the first lateral or somewhat shorter. In various forms, as for instance in H. Seideli, H. Hollandi (plate XXXTX, fig. 1 c), the two main saddles are subsymmetrically divided, each by a long and slender secondary lobe; in H. ventricosus (plate XXXVIII, fig. 4) two nearly equal second- ary lobes cut into the lateral saddle; and in H. depressus the external saddle is incised by three slender secondary lobes of equal length. Hence it is principallv the two principal saddles, and only to a lesser extent the lobes, which supply the specific differences of the suture line. The relative length of the body chamber and the shape of the aperture arc unknown. In order to arrive at a clear understanding of the genus Himalayites, a studv of the individual ontogeny is of particular importance. As far as the shape of the shell is concerned, there exists a tendency towards a relative increase in the thickness with in creasing age. ^T,7 oth-. g^era, or sub-genera, such as Stephanoceras, SphcB- roeeras, MacrocepMues, SpUiceras, Reinecki., the inner whorls are comparative^ thick, growing relatively higher later and • comparatively aged specimens, the opposite^tend cv s K T," " MnDW" b fuU"gr°W" is most pronounced in Z, , 7 °bSerVable * thc Present This somewhat higher than broad^ butTT ^ ^ V°lutioDS ™ * other species the^ ar^at Li I J" ^ bigl" - they increase more and more in Cdth T, ** ^ bUt ^^ species are not known ; 'it ie however w 1DIier™st volutions of several ness predominates, and even 'the middle^* * that Srowth in thick" decrease in relative breadth Although i°D °f tte bod7 "Camber does not ledge of the foremost part of the bodv'l meDtioned> we have no know- ascertain whether after aU a contractionTT* ^ C0D8e1u<*% are unable to cross"Section may not take place HIMALAYITES. 137 there, we are certainly in a position to declare that the predominant increase ir, the thickness of the volutions characterises the main phase of ontogenic develop- ment. Simultaneously with the changes in the cross-scction of the volutions there occur changes in the ornamentation. The innermost volutions do not yet posse* the sculpture described above, but are ornamented with fine and sharp rite which run for some distance across the flank; either in a radial direction with a slight anterior deflation, or else in a somewhat sigmoidal curve, and which, after having formed a swelling, split up into two branch-ribs which terminate each in ft fine, pointed, small tubercle on either side of a sharp median ventral groove. At this stage the sculpture recalls that of Parkinsonia as well as the immature forms of the group of Hoplites Callisto and Hoplites Wallichi. As the shell grows in size, the ribs- become gradually differentiated into tuberculiferous ribs and simple non-tuberculate ridges. The point at which the ribs divide and which in the immature stage is situated near the external margin of the volution shifts its position to about the middle of the flanks, and the knots at the point of bifurcation increase very rapidly in size. In the full-grown stage the tubercle-bearing ribs are somewhat stronger than the non-tuberculate ones. It is only when two ribs unite to form a tubercle that this strengthening of the ribs does not take place. The median furrow of the immature stage is soon lost; when the diameter has reached 25 to 35 mm., the ribs, where they cross the median line of the ventral face, are intersected by a very shallow groove or only slightly reduced, and finally only a trace of this reduction remains visible. This course of development is followed by different species to a different extent and is passed through more or less rapidly or slowly. Him. hyphasis Blanford (non Stoliczka) represents a primitive type : it is a small species with relatively high volutions in which development proceeds up to the differentiation into tuberculate and non-tuberculate ribs, but does not reach the stage where trichotomy of the ribs sets in. Only in one place does a specimen show trifurcation of a costa, and tubercle formation is yet little pronounced. Whilst, therefore, Him. kyphosis proceeds only slightly beyond the Parkinsonia stage and retains its primitive features nearly throughout life, the opposite is the case with Him. Stoliczkai: here the Parkinsonia stage is rapidly traversed; already at an early age tubercles make their appcarancc at the branching-points of the ribs, and trichotomy sets in as soon as the diameter has reached 15 mm. With a diameter of 42 mm. the same species exhibits a division of a rib into five branch-ribs. When of a diameter of 35 mm. Him. ventricosus is yet in the Parkinsonia stage, but suddenly and practically without passing through a transitional stage it develops strong tubercles and the breadth of its volutions increases at a rapid rate. In Him. Scldagintweiti, also, the Parkinsonia stage is only abandoned when the diameter has reached 43 mm., but with a diameter of 29 mm. isolated trichotomous ribs already make their appearance. Him. kutianus is yet in the Parkinsonia stage when measuring 22 to 30 mm. in diameter, but at 35 to 40 mm. it develops a soulpture which corresponds approximately to the developmental phase of Him. hyphatis ; it is only B 2 HIMALAYAN FOSSILS. 136 mm that the typical Himalayites when the diameter attains more than • sculpture establishes itself. volutions reaches its maximum, whilst it is least in Bim.*^'^ stauds Him. hoplitiformis with its what apart from the majority of <*> ^ flf which are still merely characteristic cross-section and its si dichotomous even on the body-ci.ambe ^^ groUp of the Spiti fauna, The genus Himalayites forms a M P^^ constructed forms. We cannot without transition to any int«r"relaJ ' considerable resemblance to certain Rein- faU to recognise in the adult stag ^ ^ ^ tQ certain form3 which eckfe. especially to JWn«*w BranC°** 0'f the genus ffopKto, such as Hop. have been hitherto looked upon as member* oM*^ ^ ^ ^ ^ ^ < Y^TCi^^itut. the Wallichi group, further those recall the species of Hoplites «mcn Reineckias, and perhaps also Parkinsonias which are more closely reet ^ the snecies of Perisphinctes with ventral furrow, sucn ^ Oppel Hence we have to look especially to Remeckia and tt^to for points of contact with the new genus Himalayites.