120 IIWERTEBRATE FOSSILS

l-colyx ) counter sePtum-.L$ 2-septum KL) counter-loterol septum-29 3-fossulo counter quodront*30 4--growth line olor fossulo-31 5-epitheco (A) olor septum*32 6-septol cordinol quodront-33 7-interseptol ridge cordinol fossulo-34 B--coro llite (C) cordinol sePtum-35 9-simple corol disseoiment-36 I O-opicol end dissepimentorium-37 I l-minor septum tobulo-38 l2-mojor septum tobuloriurn-39 l3-oxiol boss thecorium-40 l4-oxiol complex trobeculo--41 l5-lcmello l6-medion lomello

I 7-tobello

I B-inner woll lp-sf6rseTsns 20-phyllotheco septum--42 2l --cycthotheco' 22-tobulo corino---43 23-columello discohtinuous septum-44 24-protosepto 24o-olor septum (A I plotform---45 24b---cordinol septum (C colycol pit--46 /{6-66unfsr -acompound septum (K) corol-47 24d. --counter-lotero I septum ( KL) corollum--48 Z5-isi phonofossu lo coro llite-49 26-rnetoseptum 27-tertiory sep holotheco-50

l-tc. 4-14. Morphologic terms commonly applied to.rugose corals. The various tems are expiained briefly in the accompanying alphabeticaiiy arranged list, cross-indexed to the figule by numbers, alar fossula (31). Gap in calyx in position of an apical end (10). Pointed proximal extremity of a alar septum or adjoining it. corallite where growth begins. alar septum (24a, 32). Protoseptum located - axial boss (13). Central prominence in calyx about midway between cardinal and counter formed by an axial structure. septa, generally identifiable by pattern of axial complex (14). Differentiated structure in inserted new septa which join it pinnately on central part of thecarium formed by twisted the cotrnter sicle. (Continued on next !tagr.) COELE},{TERAT'ES 1e1

(Fig. a-74 eontinued.) \ f)counter septum-28 inner edges of septa, by tabellae and lamellae, inner wall (18). Partition approximately paratlel I /,tKL)counter-loterol or by abruptly deflected parts of tabulae. to epitheca, which may develop in various ways | septum-29 / ,/ calycal pit (a6). Localized depression in central inside thecarium. quodront-3O (7). / -counler part of calyr<. interseptal ridge Longitudinal elevation ./ fossulo-31 calycal platform (45). Flat or gently sloping part on exterior of epitheca corresponding in position '-olqr of calygal floor. to space between two septa. (Al olor septum-32 calyx (1). Bowl-shaped depression at summit of a Iamella (15). Radially disposed wall in central - 6616li6ql quodront-33 corallite, chiefly formcd by upper edges of part of corallite forming part of axial complex; scpta. may or may not be joined to a septum. - cotdinol fossulo-34 cardinal fossula (34). Gap in caiyx in position of major septum (1-2). Any protoseptum or meta- cordinol septum-35 the cardinal septum; rnay be open, when septum, distinguished from minor septa by -(C) edges of adjoining septa do notjoin, or closed, oreqter lcnofh - dissepiment-36 when they unite. median lamella (16). Wall in axiai complex in ---4i ss e or m e n to r i u m- 3 7 cardinal quadrant (33). Part of thecarium be- plane of counter and cardinal sepra. -/' tween cardinal septum and either of alar septa. metaseptum (26). Any major septum other than cardinal septum (24b,35). Protoseptum which is a protoseprum. tobuloriurn-39 adjoined pinnately on both sides by newly minor septum (11). Generally short, secondarily inserted septa. introduced septum belonging to a cycle which carina (43). Smali flangelike projection on side makes appearance nearly simultaneously be- trobeculo-41 of septum, formed by thickened trabecula. tween major septa. columella (23). Relatively solid axial structure. phyllotheca (20). Inner waIl formed by abrupt compound coral (47). Skeleton of a colonial bending and union of axial edges of septa. coral. protoseptum (24). Clne of the first-formed six continuous septum (42). Radial wall of corallite septa. formed of laterally adjoined trabeculae, or of septal groove (6). Longitudinal furrow on uninterrupted fibers or laminar tissue. exterior of epitheca in position of a septum. corallite (8, 49). Skeleton formed by an indi- septum (2). Radial wall generally extending vidual coral polyp, whether solitary or forming from peripheral edge of corallite partly or part of a colony. entirely to its axis, but in some not corallum (48). Skeletal deposit of a coral colony. extended to the periphery. counter-lateral septum (24d, 29). Protoseptum simple coral (9). Equivaient to solitary; not adjacent.to counter septum on either side. colonial. counter quadrant (30). Part of thecarium be- siphonofossula (25). Gap in calyx formed by tween counter septum and either of alar septa. localized abrupt depression of tabulae adjacent counter septum (24c, 28). Protoseptum opposite to largely suppressed cardinal septum. cardinal septum. stereozone (19). Thin or thick band of relatively cyathotheca (21). Inner wall fomed by sharp dense calcareous deposits which is formed in corol--47 deflections and union of tabulae. various ways within thecarium. acompound iliscontinuous septum (44). Radial wall formed tabella (17). Steeply inclined tabula--like lamina corollum-48 of trabeculae which are not solidly joined in central part of thecarium, generally forming together, or wall which is interrupted longi- part of an axiai complex. corollite---49 tudinaliy or peripherally. tabr:Ia (22, 38). Convex, plane, concave, or dissepiment (36). Vesicle typicaily occurring in irregular lamina extending across thecarium holotheco-50 margindl parts of thecarium, with convexly transversely, or developed only in central part curved wail toward axis of corailite. of thecarium. The various terns are explained dissepinentarium (37). Part of thecarium tabularium (39). Part of corallite occupied by I to the figure by numbers, occupicd by dissepiments. tabulae. Pointed proximal extremity of a epitheca (5). Outer wall of corallite. tertiary septum (27). Equivalent to minor septum growth begins. fossula (3). Gap or depression in floor of calyx. in classification which d:signates protosepta Centrai prorninence in calyx growth line (4). Marking on epitheca, such as as primary and metasepta as secondary. L\ial structure. slight ridge or depression parallel to margin of thecarium (40). Interior of a coraliite, consisting 14). Differentiated structure in cal1x, defining a former position of this edge. of entire space enclosed by epitheca, or equiva- f thecarium formed by twisted holotheca (50). Generally wrinkled lamina lent to such space if external wall is lacking. rtinued on nexl !ogr.) deposited by colonial corals to cover base of trabecula (41). Row of calcite fiber bundles com- corallum. prising a main structural element of septa. -l

INVER'TEBRATE FOSSIL$

Diophrogm

Diophrogm

AutoPore

Amolgomote wal

Frc. 5=3. !OSSILS x.62 INVER'|BBRAIE

2-monticule

D)+--r-s6s6slqsrn6 G Dekayella Prasopora 4-tongential section J-longi tudi nol slction 6-outoPore or zo@clum

7- mesopore 8-.cystiphrogm 9*-diophrogm Prasopora Prasopora

1 O---oconthoPore ll-omolgomotewo.ll l2-moture region l}-imrn6furs 1s9166 kutoPore or zooeci um section

I 6-longitudinol ser:tion Dekayella H Dekayella bryozoans. (A-F) prasopora conoidea ulrich, Middle Frc. 54. srrrJ*]"i'i"rtures of trepostome L^++^- nf znarirm (.s-r) .op, ^..l ";.*'c L'l;.lJi." ci:J.;ru;""*.'"' '1q',."^"j5* :*'::": "i*:-",",T,:i"T,:t T:'#: ilTi;:'?; [i#ili"f iG;il;i'""tio"', xr0"(c-1) 2'.\''l':tu:'Y:'1].,':l"1I"lj"i,,?.:il; ;l;i"d:in'firuil;:;;A;il;;;; oi 'o"i"'' xr' (H' 'I) tangentiar and ronsitudinar sections, X10. Terminology is explained below' diaphragm. (9). Thin piatform extending trans' acanthopore (10). Minute tube parallel to auto- versely across an autopore or mesopore' pores in mature region of colony, commonly region (13), Interior part of colonial proiecting at surface as a short spine' immature the proximal (initial) part u-"tg"-ut" wall (11). Coalesced wall between structure containing autoporcs, characterized by thin-walled adjacent autopores, between autopores ano of tubes having widely spaced diaphragms; area mesoPoresr or between mesoPores' autoPores. autopore (6, 14)- Relatively large tube or of budding of longitudinai section (5,16)' Thin slice ofcolony ch-amber occupied by one of the main zooids cut parallel to autoPore tubes' the colony; also termeci zooecium' of (12). Peripheral part of colony (3), Caicareous lamina, generally mature region coenelasma the distal (terminal) part ot auto- wrinkled, secreted at the base of a colony' containing characterized by thickened cystiphragm (8). Curved thin wall forming a po..r, walls and"olr-only by presence of mesopores, acantno' vesicle along the side of an autopore; com- and more closely crowded diaphragms' monly in a uniformly oriented vertical series pores, mesopore (7). Tube parallel to autoPores, com- within the autoPore. -S BRYOZOANS t63

so as to intersect the surface nearly at region which are distinctly more slender (1). right angles As shown by the begin- than the average. Also, these have more nings of the tubes, the individual zooids closely crowded diaphragms than the secrete which them originate by budding normal-sized tubes (1). Such small tubes from previously formed members of the are termed mesopores (7), for clearly they colony. As each builds a calcareous are unlike the large ones called autopores wall around itself, it moves gradually up- (pores or tubes standing by themselves, ward, abandoning the first-formed part of that is, main ones). As among modern its tube. At rather widely spaced intervals, bryozoan colonies, Dekayella which contain special- the autopore tubes are blocked offby cross ized individuals associared with thl nor- g), partitions (diaphragms, and each such mal , the trepostomes evidently partition represents a temporary floor se- included more than a single type of zooid. creted by the zooid. The diaphragms, This differentiation, or polymorphism, is therefore, are built in succession, each common among colonial invertebrates. representing a temporary halt in the build- A tangential section of the Dekayella ing of the trrbes. It follows thaf the portion colony (11) intersects the autopores and of any tube below the last-form.a aia- mesopores approximately at right angles phragm has been vacated by the zooid and thus serves to show the transverse and is not occupied by living tissue. The shape and size of the tubes. They have a diaphragms of Dekayella are complete in Prasopora distinctly polygonal form. The mesopores that they extend entirely across the tubes. are identifiable by their small diameter. Some other trepostome bryozoans have Both autopores and mesopores, which the incomplete diaphragms with a central per- thin section happens to cut between dia- lbration or reaching only part way across phragms, appear to be open, for only clear the tube. The zoological significance of crystalline calcite generally is seen as a such structures is uncertain. Obviouslv. filling of the tubes. Wherever a diaphragm the soft parts of a bryozoan could extenj occurs in the plane ofthe section, however, through the aperture of such incomplete the autopore or mesopore containing it diaphragms. A few trepostomes have no appears cloudy, because the diaphragm diaphragms at all (Figs. 5-5, 3; 5-16,7). interferes with the passage of light. In ad- Dekayella I In Dekaltella, the part of the autopores dition to these features, tangential sections near the surface 7) Prasolora conoidea Ulrich, Middle of the colony is charac- of Dekayella show scattered tiny, thick- ction, and bottom views of zoarium, terized by much more numerous and walled tubes, which are located generaily yella praenuntia Ulrich, Middle Ordo- closely spaced diaphragms than in the at angles between two or three adjoining i (H, I) tangential and longitudinal immature region (1). Also, the walls are autopores or at junctions of the walls of noticeably thicker here. Both ofthese char- autopores and mesopores. They are called (9). Thin platform extending trans- acters denote a slowing down in the out- acanthopores (acanthos, spine, /0) because oss an autopore or mesopore. ward building of the tubes, which indicates they project above the general surface of ,gion (13). fnterior part of colonial the attainment of maturitv in these parts the colony as minute spines. Acanthopores :ntaining the proximal (initial) part of the colony are confined to the mature reeions of the ces, characterized by thin-walled Longitudinal sections of Dekaltella com- colony and undoubtedly represent rg widely spaced another diaphragrrs; area monly show some tubes mature of autopores. in the specialized type of zooid. Their functions. section (5, 16). Thin slice of colony (Fig. 5-4 continued.) . to autopore tubes. monly smaller and more angular in section autopores; generally monticules are n (12). Peripheral regularly part of colony than autopores and containing more numerous spaced. the distal (terrninal) part of auto- diaphragms; presumably occupied by a special- tangential section (4, 15). Thin slice of colony monly characterized by thickened ized zooid. cut transverse to autopores near surface of ly presence of mesopores, acantho- monticule (2). Locdized, elevation of colonial colony. more closely crowded diaphragms. surface, commonly foimed by a cluster of zoarium (1). Entire bryozoan colonial skeleton. . Tube parallel to autopores, com- mesopores surrounded by larger-than-average zooecium (6, 1a). same as auropore. 1 /-A INVERTEBRATE FOSSILS cryptostome, which means hidden mouth. been made by specialized zooids' such as Some representatives of this order have occupied the tubes called mesopores and mesepores and acanthopores, which sug- acanthopores. Rather, they are deposits gest relationship with the trepostomes, but formed by living tissue of the whole colony, in the mature region of most cryptostome belonging to no particular individual bryozoans, spaces between the zooecial members, and thus may be designated as tubes are filled with irregular minute vesi- coenosteu4, whicLr means common skele- cles or a nearly solid calcareous deposit. tal subsrance (Fig. 5-8, 6). These interzooecial structures cannot have Four genera of representative crypto-

exterior, it is employed also for the opening at tlie base of the vestibule, which constitutes thc "hidden mouth" of crYPtostomes' autopore (2). One of main tubes of colony; also termed zooecium. diaphragm (9). Thin platform extending trans- versely across an autoPore. distal (3). Direction away fron initial autopore (ancestrula) of a bryozoan coiony, correspond- ing to direction of growth of successively budded autopores. hemiseptum (10). Piatform extending part wav across an autopore) designated as superior if it ,A rvall and as inlerior $-mqfuls projects from proximal if it projects from distal rvall of autoPore 9-diophrogm marks base of vestibule in some cryptostomts for a hinged lid l0--hemiseptum and possibly furnished support (operculum) for closure of tube. I l-longitudinol immature region (1). Thin-walled axial part of section--* colony, wblch reaches the surface only at lf-r6sgqsq6 growing tip of a branch. longitudinal section (11). A cut parallel to auto- lJ-1pqrararc. aec pore tubes. l4-oconthopore mature region (8). Peripheral part of colony, ridge characterized by greatly thickened interzooecial walls and by presence of acanthopores. I J-mis166sn1h6pot. megacanthopore (12). Unusually large, promi- nent acanthopore. micracanthopore (15). Relatively small acantho- Rhombopora pore, (6). Direction toward initial autopore Frc. 5-7, Structural features of cryptostome proximal (ancestrula) of a bryozoan colony, opposite to bryozoans-Rhombopora. (.4) Side view of a direction of growth of successively budded colony of Rhombopora constans Moore, Upper autoPores. Pennsylvanian (Virgilian), north-central Texas, section (13). Slice or cut normal to X10. (B) Growing tip (distal extremity) of this transverse direction of colony growth' intersecting mature species, X40. (C) Transversely and longitudinally and immature regions. cut part of colony, showing internal features, X40. vestibule (7). Outer part of autopore tube which acanthopore ridge (14). Nanow elevation runs approximately normal to surface of formed by acanthopores (megacanthopores and colony; inner limit of vestibule is malked in micracanthopores) in interzooecial areas. some cryptostomes by a hemiseptum. aperture (5). Opening of an autopore or zooecial zoarium (4). Hard parts of the whole bryozoan tube. Although this term is commonly used for colony. the outer opening, which is visible from thc zooeciurn (2). Same as autoPore" BRYOZOANS 169 ry specialized zooids, such as stome bryozoans are selected for the pur- colonies which have twielike : tubes called branches or mesopores and pose of making an acquaintance with the are unbranched; Sulcoretipora . Rather, typically has rhey are dcposits important structural features of this group: the form of a narrow ribbon.'which'mav rng tlssue ol rhe whole Rltombopora comprises slender, coiony, cylindrical branch in a Y-shaped manner like a fbrked )_ no particular individual d ma1- he designared as I 2*lunorium :li. -pseudosepto gan; (3) external view normal to plane of meso- rtnrch means common skele_ theca; (C) transverse section showing mesotheca, (Fig. 5-8, s). autopores in immature region, and dense coeno_ :a of representative steum irr matue crypto_ region; (D) longitudinal section ; all X10. (E-G) SutcoreteporaJormosa Moore, Uppe, empioyed also for ,n. op.rt* i Pennsylvanian (Virgilian), north-central Texasl e vestibule, urhich constitutes the (E) external view normal to plane of *..otheca: :h" of cryptostomes. mesotheco--6 (F) external view of edge, in plane of mesotheca: )ne of main tubes of colony; aiso (G) tangential section showing autopores at um. various depths within colony and intervening Thin platfonn extending trans_ coerlosteum; all X10. (11-J) Much enlarged views an autopore. of a hood-shaped lunarium from side, distal. and tion away from initial autopore ture region coenosteum-B proximal directions. i a-bryozoan colony, correspond_ coenosteum (8). Vesicular or dense skeletal r ofgrowth ofsuccessively budded lG-distol 4 tissue between autopores in mature region, secreted by interconnecting soft parts of ). Platform extending part whole way colony rather than by individual zooids. pore, designared as supcrior if ir distal (10). In the direction of colonial srowth. proximal *.all and as int.erior immature region (7). Thir-walled plrt of from distal rvali of autopore. colony next to mesotheca of Sulcoretebora. vestibule in some cryptostomes characterized by autopores growing rnished support parattet to for a hinged lid plane of mesotheca, r c-tosure of tube- interspace (4), Area at surface of a colony be- L (1). Thin-walled axial part of tween adjacent apertures of autopores. reaches the surface only at Iongitudinal section (5). r branch. Siice or cut of colony parallel to direction of growth of autopores. ion (11). A cut parallel to auro- Iunarium (2, 13). Thick-walled posterior (proxi_ W mal) part of autopores 8). Peripheral part belonging to some of colony, bryozoan colonies, commonly more r greatly thickened strongly interzooecial curved tr.ansversely esence of acanthopores. than distal wall anj having edges which may project as pseudosepta (12). Unusually large, promi_ into autopores; surficial portion ofsome projects as a hood over aperture. (15). Relativety sma1l acantho_ mature region (9). Peripheral part of colony characterized by interspaces ection toward between autopores initial autopore fiIled by coenosteum. r bryozoan colony, opposire to mesotheca (6). Median lamina of bifoliate rwth of successively buddecl colonies, composed of two coenelasma layez,s which form respective bases of oppositely (13). Slice or cut norma.l to growing halves ry growth, of colony. intersecting mafure peristome (12). glons. Su lcoretepora Rim surrounding an autopore aperture. :r part of autopore tube which Frc. 5-8. Structural features of cryptostome proximal (11). tely normal Direction toward beginning of to surface of bryozoans-Sulcoretepora. (l) Diagrammatic colonial growth. nit of vestibule is ma.ked in much enlarged view of a colony of Sulcoretepora pseudosepta (1) Projections ofedges ofa lunarium :s by a hemiseptum. showing structure in longitudinal section and forming Iongitudinal ridges on walls parts of the of an whole bryozoan portion of tangentially planed peripheral region autopore. qolony. of (B-D) Sutcoretepora obliqua McNair, tangential section (3). Thin slice or cut of : as autopore. colonv ]r{iddle (Cazenovian), northern Michi- near zurface of colony, transverse to autopor.:. 172 I N \1 EP.TEBRAT-E FOSSI LS

| obv€rse side-|0 -fenestrule 2-spine 3---operture 4---{utopore or zoo€clum ' -branch-]2

peristome-13 5--dissepiment

a*r.,6519urn*l 7-reverse side {

obverse side

Fenestrel I ina

reverse side

Archiriredes Fenestrellina G Frc. 5-9. Structural features of cryptostome bryozoans-Fenestrellina and Archimedes. (A) En- larged oblique view of part of the lacy network which characterizes the zoarial fronds of Fenestrellina and Archimedes, branches transversely and tangentially sectioned at front of the dralving. (B) Part of the zoarium o! Archimedes uortlteni (Hatl), X1, Mississippian, Illinois, showing screwlike axis of the colony and spiraliy aranged network attached to the central support. (C) Diagram of the funnel-like zoarial form of some species of Fenestrellina, showing extensions for support at the base. (D) Diagram of the spirally arranged fronds of the Arclimerles zoarium. (E-G) Fenutrellina pectinis Moore, X10, Upper Pennsylvanian (Virgilian), north-central Texas; obverse, edge, and reverse sides of part of a colony. acanthopore (6). Slender dense-walled tube axis (9). Solid calcareous support of Archimedes. 'arhich projects as a node or spine at sruface; branch (12). Slender rodlike structure of fenes, arranged along mid-part of branches of many trate colonies extending outward radiaJly from fenestrate bryozoans. base, place of attachment, or point of bifurca- aperture (3). Opening of zooecium at surface. tion; it bears zooecial chambers. which have autopore (4). Chamber occupied by an indinidual apertures on one side of branch only. zooid, very short in fenestrate bryozoans and carina (11). Median keel running along side of having ovoid, pentagonal, or hexagonal outline branches which bears zooecial apertures, as seen in tangential sections; also cailed coenosteum (14). Dense or vesicular calcareous zooeclum. tissue formed by interzooecial cells of bryozoan (Continued on next Page.) BRYOZOANS ttJ D). FenestrelLina-like networks grew out of the geologic column. A few species have from the flanges of this axis. Tius, Arrhi- been found in Pennsylvanian rocks of medes differs from Fenestrel/ina essentially in western North America and in the spiral struclure of the colony and in its deposits of Russia (Fig. 5-16). solid screwlike centritl support. Colonies of Archimedes showing parts of Ctenostorne Bryozoans the spreading fronds attached branch-12 to the solid The comb-mouth br.yozoans, or cteno_ spiral axis can be found places. in many stomes, are characterized by the growth of Generally, however., the clelicate licelike individuals which bud from internodes parts of the colony of a are broken away from tubular stem (stolon), which is attached the axis and the latler, which is much throughout its length to a shell or some more stur-dy, is found alone (Fig. 5_12, 4). other foreign object (Fig. 5-10). Since the lacelike parts of Archimedes djffer co€nosteum_l4 in no way from Fenestrellina, it is dilicult -- to identify such networks if they are found I separated from thc spiral axis. Some iso_ obverse side lated fragments of lacy bryozoans classed as Feneshellina rnay actualiy belong to Archimedes, because oniy the spiral axis distinguishcs thcse two genera. Thickness and spacing of the spiril flanees on thc axis of Archimedes are characteri usclul in discriminating species. The lacy parts be_ lb Ionging to many spccies is unknown. vinella Rhopalonaria A recent suggestion that the screwlike Frc. 5-10. Fossil cterrostome bryozoans. (la, b) axis of Archimedes was produced b1, 1in1s_ Vinella repens Ulrich, Middle (Black_ secrering aigae which grcw jn symbiotic riveran), Minnesota: (1a) srolons of colonies union with lenestreljinid bryozoans does attached to interior ofbrachiopod she[, (10) not accord with X1; consrancy of characrers of portion of radiating stolons showing regularly the spiral axes. Also, microscopic structure spaced minute pores which mark piaces of attactr_ of the axes corresponds ro thar of thickened ment of bryozoan individuals, X10. (2) Rhopa- parts of the lacework branches and to the lonaria uenosa Ulrich, Upper Ordovician (Cin_ cinnarian), southern Fenestrellina G branching roots of Fenestrellina. Accord_ Ohio; spindle_shaped shallovr ingly, the screwlike excavations in shell on which this ctenostome rellina and Archimedes. (A) En- axis of Archimedes seetns colony grew, with threadlike stolonal connec_ he zoarial fronds of Fenesh.ellina to be the product of secretion by extra_ and, tions, X10. t of the drawing. (B) part of the zooecial cclls of the colony, and its ma_ owing screwlike axis terial may bc termed of the colony coenostcum. In an unexplained manner, possibly Diagram - by of the funnel-like zoarial Archimedes is abundant in some Lower chemical solution of the at the base. (D) cul.ar"o.,s ,,rb_ Diagram of the and Upper Mississippian fornations, and sta.nce of shells which furnish llina pectinis Moore, X10, lJpper the base, the genus belongs essentially to this part some ctenostome reverse sides of part of a colony. stolons, such as Rlzapa_ calcareous support of Archimedes. (Fig. 5-9 continued.) ilender rodlike structure of fenes- colony, rather than by any individual zooid. reverse side (7). Surface of colony extending outward dissepiment a lacking radially from (5). Crossbar connecting branches of autopore apertures. f atrachment, or point of bifurca- a lacy bryozoan, spine (2), Surficial projection formed by an r zooecial chambers, which have u'1,::t*:^ j1L by. adjacent 'u"""ri..p.'".lJ,J*J.tlil;",;;.;;.;; one side of branch only. breitrches and dissepiments,9flt* .*"T"1 of a lacy _ bryozoan. branch, generally lo".,.Jorrl ;;;'"."''*"-' .edian keel running along side of obverse side (10). Surface ofcolonywhichbears zoarium (B). Har{ parts of entire bryozoan ch bears zooecial apertures. autopore apertures colony. 4). Dense or vesicular calcareous peristome (13). Rim partly or entirely encircling zooecium (4). Same as autopore. by interzooecial cells of bryozoan an autopore aperture. -!

Cardinal septum Cardinal septum Cardinal sept and fossula

Septum - Tabu la

Dissepiments

Alar septum Counter septum ----,,j Growth lrnes { rug ael

B c

Exsert septum

1...,."J Colu mella

Theca H Costa

Septa

Dissepiments in coenosteum

Corallite

Septum Theca Columella

Coenosa rc

Theca (wall)

Dissepirnents in coenosteum

Tabula in corallite

Columella K

Figure 11.6. Principal morphologic features of the skeleton of (Devonian rugosan, x 1) showing bilaterally symmetrical rugose and scleractinian corals. A, Srylized solitary rugose coral arrangement of septa along the cardinal-counter plane. Two (minor skeleton septa_omifted for clariry); the polyp lied in the cardinal sectors or quadrants are clearly marked on each side of calice at the top of the corallum. A cutaway viiw shows the the cardinal fossula as are the two alar fossulae; the rwo counter relationship of septa, tabulae, and dissepimenrs; nore that the sectors (quadrants) are not as clearly separated, due to the lack outer surface of the wall is grooved at rhe position of internal of a counter fossula. C, Side view of the same specimen showing septa. B, Calice view of silicified corallum of Kionelasma periodic rejuvenation or growth cyclicity (rugae) and septal

t. &z:.