»«***, 1301 W.6RKN ST. - STATE OF ILLINOIS DWIGHT H. GREEN, Governor DEPARTMENT OF REGISTRATION AND EDUCATION FRANK G. THOMPSON, Director DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON, Chief URBANA REPORT OF INVESTIGATIONS— No. 113 KINKAID CORALS FROM ILLINOIS AND AMPLEXOID CORALS FROM THE CHESTER OF ILLINOIS AND ARKANSAS BY WM. H. EASTON Reprtnted from Journal of Paleontology, Vol. 19, Nos. 4 and 6, 194S PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS 1.945 ORGANIZATION STATE OF ILLINOIS HON. D WIGHT H. GREEN, Governor DEPARTMENT OF REGISTRATION AND EDUCATION HON. FRANK G. THOMPSON, Director BOARD OF NATURAL RESOURCES AND CONSERVATION HON. FRANK G. THOMPSON, Chairman NORMAN L. BOWEN, Ph.D., D.Sc, LL.D., Geology ROGER ADAMS, Ph.D., D.Sc, Chemistry LOUIS R. HOWSON, C.E., Engineering CARL G. HARTMAN, Ph.D., Biology EZRA JACOB KRAUS, Ph.D., D.Sc, Forestry ARTHUR CUTTS WILLARD, D.Engr., LL.D. President of the University of Illinois GEOLOGICAL SURVEY DIVISION M. M. LEIGHTON, Chief SCIENTIFIC AND TECHNICAL STAFF OF THE STATE GEOLOGICAL SURVEY DIVISION 100 Natural Resources Building, Urbana M. M. LEIGHTON, Ph.D., Chief Enid Townley, M.S., Assistant to the Chief Velda A. Millard, Junior Asst. to the Chief Helen E. McMorris, Secretary^ to the Chief Effie Hetishee, B.S., Geological Assistant GEOLOGICAL RESOURCES Ralph E. Grim, Ph.D., Petrographer and Principal Geologist in Charge Coal G. H. Cady, Ph.D., Senior Geologist and Head L. C. McCabe, Ph.D., Geologist (on leave) R. J. Helfinstine, M.S., Mech. Engineer Charles C. Boley, M.S., Assoc. Mining Eng. Bryan Parks, M.S., Asst. Geologist Earle F. Taylor, M.S., Asst. Geologist (on leave) Ralph F. Strete, A.M., Asst. Geologist Robert M. Kosanke, M.A., Asst. Geologist _ Robert W. Ellingwood, B.S., Asst. Geologist George M. Wilson, M.S., Asst. Geologist Arnold Eddings, B.A., Research Assistant (on leave) Raymond Siever, B.S., Research Assistant (on leave) •John A. Harrison, B.S., Research Assistant (on leave) Mary E. Barnes, B.S., Research Assistant Margaret Parker, B.S., Research Assistant Elizabeth Lohmann, B.F.A., Technical Assistant Oil and Gas A. H. Bell, Ph.D., Geologist and Head Frederick Squires, B.S., Petroleum Engineer Stewart Folk, M.S., Assoc. Geologist (on leave) Ernest P. DuBois, Ph.D., Assoc. Geologist David H. Swann, Ph.D., Assoc. Geologist Virginia Kline, Ph.D., Assoc. Geologist Paul G. Luckhardt, M.S., Asst. Geologist (on leave) Wayne F. Meents, Asst. Geologist James S. Yolton, Asst. Geologist Margaret Sands, B.S., Research Assistant Industrial Minerals J. E. Lamar, B.S., Geologist and Head H. B. Willman, Ph.D. Geologist Robert M. Grogan, Ph.D., Assoc. Geologist Robert T. Anderson, M.A., Asst. Physicist Robert R. Reynolds, M.S., Asst. Geologist Margaret C. Godwin, A.B., Asst. Geologist Clay Resources and Clay Mineral Technology Ralph E. Grim, Ph.D., Petrographer and Head Richards A. Rowland, Ph.D., Asst. Petrographer (on leave) William A. White, B.S., Research Assistant Groundwater Geology and Geophysical Exploration Carl A. Bays, Ph.D., Geologist and Engineer, and Head Robert R. Storm, A.B., Assoc. Geologist Arnold C. Mason, B.S., Assoc. Geologist (on leave) Merlyn B. Buhle, M.S., Asst. Geologist M. W. Pullen, Jr., M.S., Asst. Geologist Charles G. Johnson, A.B., Asst. Geologist (on leave) Margaret J. Castle, Asst. Geologic Draftsman Robert N. M. Urash, B.S., Research Assistant Areal and Engineering Geology George. E. Ekblaw, Ph.D., Geologist and Head Richard F. Fisher, M.S., Asst. Geologist Stratigraphy and Paleontology J. Marvin Weller, Ph.D., Geologist and Head Chalmer L. Cooper, Ph.D., Geologist Heinz A. Lowenstam, Ph.D., Assoc. Geologist Subsurface Geology L. E. Workman, M.S., Geologist and Head C. Leland Horberg, Ph.D., Assoc. Geologist Frank E. Tippie, B.S., Asst. Geologist Paul Herbert, Jr., B.S., Asst. Geologist Marvin P. Meyer, B.S., Asst. Geologist Elizabeth Pretzer. A.B., Research Assistant Ruth E. Roth, B.S., Research Assistant Physics R. J. Piersol, Ph.D., Physicist B. J. Greenwood, B.S., Mech. Engineer GEOCHEMISTRY Frank H. Reed, Ph.D., Chief Chemist (on leave) Carol J. Adams, B.S., Research Assistant Coal G. R. Yoke, Ph.D., Chemist and Head* Herman S. Levine, B.S., Research Assistant Industrial Minerals J. S. Machin, Ph.D., Chemist and Head Delbert L. Hanna, A.M., Asst. Chemist Fluorspar G. C. Finger, Ph.D., Chemist and Head Oren F. Williams, B.Engr., Asst. Chemist Chemical Engineering H. W. Jackman, M.S.E., Chemical Engineer and Head P. W. Henline, M.S., Assoc. Chemical Engineer James C. McCullough, Research Associate Donald M. Fort, M.S., Asst. Chemist James H. Hanes, B.S., Research Assistant (on leave) Leroy S. Miller, B.S., Research Assistant (on leave) X-ray and Spectrograph W. F. Bradley, Ph.D. Chemist and Head Analytical O. W. Rees, Ph.D., Chemist and Head* L. D. McVicker, B.S., Chemist Howard S. Clark, A.B., Assoc. Chemist William F. Wagner, M.S., Asst. Chemist Cameron D. Lewis, B.A., Asst. Chemist William T. Abel, B.A., Research Assistant Melvin A. Rebenstorf, B.S., Research Assistant Jean Lois Rosselot, A.B., Research Assistant MINERAL ECONOMICS W. H. Voskuil, Ph.D., Mineral Economist Douglas F. Stevens, M.E., Research Associate Nina Hamrick, A.B., Research Assistant Ethel M. King, Research Assistant PUBLICATIONS AND RECORDS George E. Ekblaw, Ph.D., Geologic Editor Chalmer L. Cooper, Ph.D., Geologic Editor Dorothy E. Rose, B.S., Technical Editor Meredith M. Calkins, Geologic Draftsman Beulah Featherstone, B.F.A., Asst. Geologic Draftsman Willis L. Busch, Principal Technical Assistant Portia Allyn Smith, Technical Files Clerk Leslie D. Vaughan, Asst. Photographer Assistant Chief Chemist Chief Chemist. interim of absence of Consultants: Ceramics, Cullen W. Parmelee, M.S., D.Sc, and Ralph K. Hursh, B.S., University of Illinois Mechanical Engineering, Seichi Konzo, M.S., University of Illinois Topographic Mapping in Cooperation with the United States Geological Survey. This report is a contribution of the Stratigraphy and Paleontology Division. July 15, 1945 Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/kinkaidcoralsfro113east Journal of Paleontology, vol. 19, no. 4, pp. 383-389, 8 text figs., July 1945 KINKAID CORALS FROM ILLINOIS WM. H. EASTON Illinois State Geological Survey, Urbana Abstract — Three species of corals from southern Illinois are discussecL Two are good guide fossils and aid in correlating the Kinkaid limestone of Illinois and the Pitkin limestone of Arkansas. One new genus and one new species are described. introduction The coral species occurring in beds 11 and C, i , , ,, • i'i v 13 also are present in the upper part of the orals are abundant locally in the Kin- _. , . . v . , * , / i . ., ,. c ,, T,r • i . Pitkin formation of western Arkansas (col- kaid limestone of southern Illinois but , . , , , , _..... v , 1-1 u 4-u lections from the base of the Pitkin in west- only one place is known where species other ■■ ,« .i . t -j.7 j^i -n-t ern Arkansas actually are trom the upper than the ever-present Tnplophilhtes may ■ . J ■ ^ , „ , , /T 1O0C Qn>. a .• part of the lormation as a whole). Other be collected (Lamar, 1925, p. 80). A section F . . . _,. , . , '. , , ,, / ,, i , inn „i„ corals occurring in the Pitkin have not been measured there (a gully about 100 yards . & T „ . ■ r ., j o /i -i f-u f r^ ^^^ observed in the Kinkaid. JNevertheless, two west of the road, 0.4 mile north ol Cedar . . . , . . ' . r ru u - 4-u \TT7i tvt\a7i o^ ^1 oi the species common to both lormations Grove Church, in the NK£, JNWt, sec. 31, ^ , , . t 1 1 c t? o t? T^«n™ ri«««+„ Tiif'nn;'o'. are so unusual as to suggest close correla- r. 11 S., K. 2 h.., Johnson County, Illinois) . . .&&, f ., tion ol the zones in which they occur. Corals is as follows: ■* Thickness Ft. in. Pennsylvanian Caseyville group (Wayside formation) 17-19. Sandstone and platy shale Mississippian or Pennsylvanian 14-16. Shale, gray, partly sandy or plastic, pooily exposed 6 9 Mississippian Elvira group Kinkaid limestone 13. Limestone and shale. Argillaceous, fossiliferous limestone which weathers brown, interbedded with gray and buff shale. Carries abundant Triplophyl- lites and Kinkaidia in the limestone 3 6 12. Shale, dark gray, and blue-gray shale, probably with some thin limestone lenses. Partly covered 5 10 11. Limestone, gray, locally granular or nodular, in 9- to 18-inch beds. Highly fossiliferous; crinoid stems, large Archimedipora, and horned and colonial corals especially common. No brachiopods observed 16 — Carries abundant Caninostrotion in lower part. 10. Shale, dark gray and blue-gray, plastic, with dark gray, granular limestone nodules 2 7 9. Limestone, gray, locally granular, fossiliferous 18 4 8. Shale, dark gray, partly concealed . . . 1 10 7. Limestone, thin-bedded, slabby, gray. Profusion of Myalina sp. Also numer- ous brachiopods 1 7 6. Shale, greenish gray, soft. Partly concealed 4 1 5. Shale, nodular, hematite-red color 4 3 4. Shale, green-gray clay shale, the lower part of which contains angular nodules of dense, gray semilithographic limestone, and grades downward into the bed below 4 — 3. Limestone, nodular, dense, gray. Lower portion contains layers of shale and dark gray siliceous limestone 10 — 2. Shale, with nodules of dense gray limestone. Partly concealed 10 6 1. Limestone, siliceous, dark gray, with irregular cherty banding 2 — 98 — 383 384 WM. H. EASTON are considered very sensitive to environ- mental changes, hence, it appears that mi- grational routes must have existed between the Kinkaid sea of Illinois and the Pitkin sea of Arkansas. Caninostrotion is abundant in the upper part of the Pitkin and common in only one observed bed of the Kinkaid, but on the other hand Kinkaidia is abundant in one bed near the top of the Kinkaid and has only been reported once from the (upper part of the) Pitkin. Considerably more work must be done on these faunas, especially on that of the Kinkaid, before definitive con- clusions can be reached regarding connection of the seas. Even so, a partial emendation of the writer's previous views is in order. The writer has stated (Easton, 1943, pp. 128-129) that "faunal migration from Europe or Asia apparently reached this ocean [lying south of North America] and certain corals of unique aspect migrated northward with the Pitkin sea but were un- able to cross into the Illinois Basin," and that "there appears to be no evidence that the two basins were directly joined in Pitkin time." The extension of knowledge presented in this paper concerning the geographic dis- tribution of the corals shows that the two basins probably were connected and that favorable ecologic conditions of unknown duration enabled faunal migration of some distinctive organisms. Not all of the Pitkin corals are yet known to have lived in the Illinois region during Kinkaid time and many other distinctive faunal elements either remain undiscovered in strata of the adjacent seas or actually did not cross a possible ecologic barrier between the seas. ACKNOWLEDGMENTS Collections were made with the assistance of Mr. C. L. Cooper and Mrs. Phoebe Beall Easton. Mr. G. A. Cooper lent Pitkin mate- rial for study and Mr. J. E. Lamar con- tributed information concerning his work at the Kinkaid locality. SYSTEMATIC DESCRIPTIONS The morphologic terminology used in this paper has been outlined previously by the writer (Easton, 1944). Phylum Coelenterata Class Anthozoa Order Tetracoralla Family Metriophyllidae Genus Kinkaidia Easton, n. gen. Diagnosis. — Simple, curved to cylindri- cal, rugose corals; counter septum long, may be rhopaloid; pair of counter-lateral septa bordering counter septum rather long, may be rhopaloid; cardinal septum short except in young stages; alar septa long, may touch counter septum even in mature stage; other major septa of equal strength, withdrawn from axis in mature stage, commonly rho- paloid; minor septa rudimentary; tabulae distally arched, both complete and incom- plete types present; tabellae sparse, broadly arched; dissepiments absent. Genotype. — Kinkaidia trigonalis, n. sp. Remarks. — This genus differs from Clavi- phyllum Hudson, 1942, in having long alar septa in late stages, a relatively long coun- ter-lateral septum on each side of the coun- ter septum, and tent-like rather than globose tabellae. The two genera are very closely related, Kinkaidia being a potential ancestor of Claviphyllum ; the former could give rise to the latter by reduction in length, of the alar septa, by insertion of short septa be- tween the counter septum and the counter- lateral septa, and by increase in complexity of the tabellae. Sochkineophyllum Grabau, 1928, is also related to Kinkaidia, differing from it in the absence of long alar septa and the long coun- ter-lateral septum on either side of the counter septum, and in having several pairsof long rhopaloid (axially swollen) major septa. Malonophyllum Okulitch and Albritton, 1935, though possessing the same general characters as the foregoing genera, lacks tabulae. Lophophyllidium Grabau, 1928, may have been derived from Kinkaidia by reduction in length of the alar septa and by loss of the rhopaloid character of the major septa in late stages. The two genera resemble each other in the relative lengths of major septa (other than alars), in the nature of the ta- bulae, in the absence of dissepiments, and in the inconsistent development of minor septa. The stratigraphic occurrence of these KINK A ID CORALS FROM ILLINOIS 385 two genera suggests that Kinkaidia might be the possible ancestor of Lophophyllidium. Claviphyllum, on the other hand, was con- temporaneous with Kinkaidia, Kinkaidia trigonalis Easton, n. sp. Figures 1-7 Externals. — -Medium size, almost genicu- late; calyx very deep; epitheca thick, bearing prominent interseptal ridges, septal grooves, encircling striae and rugae; cardinal fossula probably pronounced; alar pseudofossula indicated. Transverse sections. — In early ephebic stage (diameters 4.1 by 6.0 mm.) counter septum very long, almost in contact with relatively long cardinal septum; alar septa long but not reaching axis; counter-lateral septum on either side of counter septum slightly longer than other metasepta; four septa in each counter quadrant, three in each cardinal quadrant; septa noticeably swollen axially ; tabular intersections sparse. In middle ephebic stage (diameters 7.6 by 7.7 mm.) counter septum and both alar septa about equal in length, meeting axially; cardinal septum very short, flanked on one side by three and on other by four meta- septa which tend to lean toward cardinal septum; counter-lateral septum on either side of counter septum extend half of radius; counter quadrant contains five, the other, six septa; most septa axially swollen; tabular intersections common; minor septa sug- gested by only slight swellings of epitheca between majors. At very slightly later stage another speci- men has 25 major septa; counter septum long, much swollen axially; each neighboring counter-lateral septum long, one alar short; neither alar septa nor cardinal septum dis- tinguishable; rudimentary minor septa pres- ent in most loculi. In very late ephebic stage (diameters 10.7 by 10.7 mm.), 24 major septa, alternating with equal number of short minor septa; counter septum very long; alar septa long, not quite reaching counter septum; counter- lateral septum on either side of counter sep- tum extends two-thirds of radius; cardinal septum short; four metasepta in one cardi- nal quadrant and three in other lean to- ward cardinal septum; counter quadrants contain six and seven septa; most majors rhopaloid. Longitudinal section. — Tabulae both com- plete and incomplete, with rather sharply down-turned borders, slightly convex dis- tally; tabellae broadly arched toward inter- section of counter septum. Remarks. — This species has been listed by the writer as "cup coral unidentified" (Easton, 1943, p. 130) from the Pitkin for- mation. Ontogeny. — -In earliest brophic stage (fig. la) only the epitheca is present, there being no septa or tabulae. The cardinal septum and the counter septum are inserted first to form an axial plate (fig. lb). The right alar then appears (fig. lc), followed by the left alar. At this stage, the top of the right alar has shifted somewhat axially (fig. Id). Later the four primary septa become thickened, the alars move to positions nearly at right angles to the cardinal-counter plane and one alar septum is separated from axial contact with the other septa, the cardinal and coun- ter septa separate slightly, and a tabula appears (fig. le). Metasepta, traceable as septal grooves on the epitheca, are inserted in the counter quadrants but are not al- ways discernible in the thecarium (fig. If). By early neanic stage (fig. lg) metasepta oc- cur withinthe thecarium in thecardinal quad- rants and tabulae are common; one counter- lateral septum is noticeably longer than the neighboring septa and is axially swollen. In early ephebic stage (fig. 4) there are 4 slightly rhopaloid septa in the counter quad- rants and 3 in the cardinal quadrants; the counter septum is long and the cardinal sep- tum is short; the counter-lateral septa are slightly longer than the neighboring septa. The typical features are observed in middle ephebic stage (fig. 6) where the counter septum and the alar septa meet axially, the cardinal septum is short, the counter-lat- erals are long; 5 or 6 septa occur in the counter quadrants and 3 or 4 are present in the cardinal quadrants, most of them being axially swollen; tabulae are common and may bear traces of septal extensions as spines. A section through a calyx at this stage gives indications of a pronounced car- dinal fossula and observable alar pseudo- fossula (fig. 2a). In late ephebic stage (fig. 3) 386 WM. H. EASTON Figures 1-7 KINK AID CORALS FROM ILLINOIS 387 the counter septum is markedly rhopaloid and rudimentary minor septa appear. Axial fusion tends to be dissipated in very late ephebic stage (fig. 4b), the majors are sinu- ous and axilly swollen, and minor septa are pronounced. Occurrence. — Specimens were collected by the writer from bed 13 of the measured sec- tion at the Illinois locality. One specimen, collected by G. A. Cooper from the base of the (upper part of the) Pitkin formation, 3 miles east of Elkins, Arkansas, was lent for study. Material. — The following specimens are in the collections of the Illinois State Geologi- cal Survey: holotype no. 3512; figured para- types no. 3513; unfigured paratypes no. 3514. Figured plesiotype: U. S. National Museum. Family Hapsiphyllidae Grabau emend. Easton, 1944 Genus Triplophyllites Easton, 1944 Remarks. — Triplophyllites was proposed for specimens generally identified as "Trip- lophyllum" in the United States. For a complete diagnosis of the genus and a dis- cussion of its relationships, see Easton 1944, pp. 35-42. Triplophyllites palmatus Easton Triplophyllites palmatus Easton, 1944, Illinois Geol. Survey, Rept. Inv. 97, p. 35, pi. 8, figs. 1-6. Remarks. — This species has been differen- tiated on the following characters (Easton, 1944, p. 36). "T. palmatus differs from T. spinulosusa (Grove) in having the cardinal septum short- ened by early ephebic stage; by its pro- nouncedly palmate grouping of septa in the counter quadrants, its very strong counter septum, and by the early reduction in the length of the cardinal septum. The generally trochoid shape, the very deep calyx, the strong interseptal ridges, and the sparse spines furnish external identifying charac- ters." This species has been figured recently in detail (Easton, 1944, pi. 8). Family Caniniidae Genus Caninostrotion Easton, 1943 Diagnosis. — (Easton, 1943, p. 134) Compound rugose corals multiplying asexually chiefly by "peripheral increase" but possibly also by basal division. Cardinal fossula conspicuous in all but early stages, formed by down-bending of tabulae and shortening of cardinal septum. Dis- sepimentarium broad; dissepiments tend toward anguloconcentric pattern. Pseudocolumella inter- mittently developed, variable, formed by junc- tion of axial ends of some major septa combined with distal arching of tabulae. Tabulae strong, irregularly arranged. Typically, septa are equally thickened in all quadrants. Caninostrotion variabilis Easton Figures 8a, 8b Caninostrotion variabilis Easton, 1943, Jour. Paleontology, vol. 17, no. 2, p. 134, pi. 21, figs. 14-16. Externals. — Conical proximally, cylindri- cal distally; calyx deep, with septal traces on floor, steep-walled near floor, oblique near periphery; epitheca thin. Transverse section. — In late ephebic stage (diameters 21 by 23 mm.) dissepimentarium extends half of radius, consists of irregular anguloconcentric, concentric and herring Explanation of Figures 1-7 Kinkaidia trigonolis, n. gen. and n. sp.; X5; (p. 385) la-lg — Successive, reversed, serial transverse sections from aseptate earliest brephic stage through early neanic stage. 2a — Transverse section in open calyx ; 2b, reversed transverse section near close of brephic stage. 3 — Reversed transverse section in late ephebic stage with rudimentary minor septa. 4a — Reversed transverse in early ephebic stage; 4b, transverse section in very late ephebic stage showing short secondaries and very long counter-laterals. 5 — Transverse section in late ephebic stage; U. S. National Museum specimen from Pitkin for- mation. tf-— Reversed transverse section in middle ephebic stage; holotype; Illinois Geological Survey No. 3512. 7 — Longitudinal section. All figures except 5 and 6 are of plesiotypes; Illinois Geological Survey No. 3513. 388 WM. H. EASTON Fig. 8. — Caninostrotion variabilis Easton; plesiotypes; X5. 8a, Longitudinal section; 8b, transverse section; Illinois Geological Survey No. 3517 (p. 387). KIN RAID CORALS FROM ILLINOIS 389 bone patterns with chevron-like dissepi- ments bordering major septa near epitheca; major septa extend three-fourths of radius, dilated within tabularium, weak to partially obsolete within dissepimentarium; cardinal septum short, flanked by somewhat pin- nately arranged major septa; counter sep- tum long; minor septa obscure to obsolete. Longitudinal section. — Dissepiments of unequal size, slightly elongate; tabulae com- plete and incomplete, with moderately down-turned peripheries and axial portions slightly arched distally; tabular density about 22 per cm.; pseudocolumella intermit- tently present. Remarks. — Although smaller than the original specimens from the Pitkin forma- tion, these Illinois corals have no other dif- ferentiating characteristics and are there- fore considered conspecific with C. variabilis. Manuscript received April 6, 1944. The species has been previously listed as "Cup coral n. gen. et. n. sp." (Easton, 1942, p. 84) from the Pitkin formation. Occurrence. — Common near base of bed 11 of the measured section at the Illinois locality. Material. — Figured plesiotypes: Illinois State Geological Survey No. 3517; unfigured plesiotypes: No. 3518. BIBLIOGRAPHY Easton, W. H., 1942, Pitkin limestone of north- ern Arkansas: Arkansas Geol. Survey Bui. 8. , 1943, The fauna of the Pitkin formation of Arkansas: Jour. Paleontology, vol. 17, no. 2, pp. 125-154. , 1944, Corals from the Chouteau and related formations of the Mississippi valley region: Illinois Geol. Survey Rept. Inv. 97. Lamar, J. E., 1925, Geology and mineral re- sources of the Carbondale quadrangle: Illinois Geol. Survey Bull. 48. Journal of Paleontology, vol. 19, no. 6, pp. 625-632, pls. 85-87, 1 text fig., November 1945 AMPLEXOID CORALS FROM THE CHESTER OF ILLINOIS AND ARKANSAS WM. H. EASTON Abstract — Three new corals are described from the Paint Creek, Golconda, and Fayetteville formations, and one from the Renault is redescribed. The ontogenies of three species are discussed and figured in detail. Possible phylogenetic relation- ships are considered. Protosepta are inserted in this order: axial septum, left alar septum, right alar septum, left counter-lateral septum, and right counter-lateral septum. INTRODUCTION This study is offered to bring to light three new species of Chester corals which can be used in correlation and to pre- sent detailed discussions of the ontogenetic development of Chester species generally referred to Amplexus. A large number of specimens was studied, many of which pos- sessed complete apical portions. septal insertion and phylogeny Two recent papers contain excellent bib- liographies of ontogenetic studies of rugose corals. Grove (1934) has presented a detailed objective review of the principal studies of fossil corals and Hill (1935, pp. 505, 506) has published a very concise statement of the septal arrangement among the rugose corals, which is quoted below. Insertion of meta-septa takes place at four points,1 immediaately on each side of the cardi- nal septum, and on the counter side of each alar septum. Referring, first to the cyathaxonid type, inser- tion of meta-septa is always accompanied by in- sertion of minor septa as follows [fig. lb]: — 2 On each side of the cardinal [C] and both counter-la- teral [CL] septa a new short septum arises. Those [IX] on the counter side of the counter-lateral septa remain short and are minor septa; the oth- ers [1] lengthen, and immediately on each side of them a new short septum arises. That on the counter side [2X] remains short and is a minor septum; that on the cardinal side [2] lengthens to become a major septum, and two new short septa are inserted one on each side of this new major septum, the one on the counter side [3X] being a minor septum, and the other [3] growing to be- come a major septum, and so on. 1 Exceptions are known. 2 This and subsequent brackets are the writ- er's. In a second group [fig. la, the zaphrentid type], by far the largest, at first after the insertion of the six proto-septa, only meta-septa arise at the four points of insertion, and minor septa (which in this group are obviously delayed) later appear in rapid succession in all the loculi, after which ma- jor and minor septa arise at each point of inser- tion as in the first group. It is not yet fully agreed as to whether the rugose corals have four or six primar}' septa, the counter-lateral septa being called metasepta by some students. Disregarding the philosophical implications, however, it has been demonstrated that the order of insertion cf the first six septa is as reviewed by Grove (1934, pp. 119, 120): I. A single septum stretches entirely across the calicle, from wall to wall. At a considerably later stage this breaks near the center, the two halves forming the cardinal and counter septa. This first formed septum Carruthers designated as the "axial septum." II. Two new septa arise, one on either side of the axial septum, at its cardinal end. These re- main attached to the wall of the corallum and to the axial septum, but gradually spread outwards, and eventually become the alar septa. III. A second pair of septa appear at the counter end of the axial septum, and similarly spread outward, but to a much more limited ex- tent than the first pair. Grove goes on to say that the "disruption of the axial septum completes the formation of six primary septa," but this does not always happen at this stage; indeed, it may not happen until a much later stage, if at all. All four of the amplexoid corals considered here have the zaphrentid type of septal in- sertion. The species restricted to the Paint Creek formation differs from the others in having an early mature stage in which the septa of the counter quadrants are dilated and in having short or rudimentary minor 625 626 WM. H. EASTON septa in very late mature stages. This species appears to be related to Amplexus rock- fordensis Miller and Gurley. The other three species are apparently closely related mem- bers of the Hapsiphyllidae. The nature of septal insertion and the presence of cardinal CT IX CTCC Fig. la, b. — Principal systems of insertion of septa in the rugose corals, la, "zaphrentid" type; lb, "cyathaxonid" type; A, alar septum; C, cardinal septem; CL, counter-lateral sep- tum; CT, counter septum; 1-4, major meta- septa; 1X-4X, minor metasepta. (Modified from Hill, 1935.) fossulae and of alar pseudofossulae at some stage in each of these species are strong argu- ments for assigning such a relationship. Early septal insertion in these amplexoid corals as found by the writer starts with an aseptate condition, after which the axial septum appears. The left alar is next in- serted, followed by the right alar, the left counter-lateral, and the right counter- lateral septa in that order. The first meta- septum is inserted in the left counter quadrant and the second metaseptum is in- serted in the right counter quadrant. Axial fusion of the primary septa tends to persist into mature stages. This order of insertion is somewhat at variance with that commonly understood to obtain in that most writers have found the alar septa to be inserted simultaneously as a pair, followed by the counter-lateral septa also as a pair. The writer (Easton 1945, p. 385) found that the right alar system was the first to be inserted after the axial septum in Kinkaidia trigo- nalis. Contratingent minor septa, which lean toward the counter quadrants and are joined to the next adjacent major septa are well known and aid in rapid orientation of sec- tions, but the writer is not aware that any- one has pointed out the apparent contra- tingent nature of tabular intersections near the epitheca in those corals in which the pe- ripheral edge of a tabula slopes from the counter position proximally toward the cardinal position. This feature can be used to orientate sections (pi. 87, figs. 12, 13) in which the septa are not capable of dif- ferentiation on other grounds. The writer noticed several abnormalities of septal relationships during this work. The amplexoid trend is apparently increas- ingly strong as maturity progresses, but some septa in early stages may be with- drawn after insertion. The position of a septum may be clearly established from study of septal grooves, but the actual in- sertion of the septum may be retarded. Oc- casionally, one will find in the counter quadrants a metaseptum attached to the alar septum for a time, rather than to the next preceding metaseptum. The rate of septal insertion is subject to wide extremes of variation in a single species, as exemplified by very rapid insertion of septa, followed by very slow insertion. Examples in which one of a pair of quadrants contains more meta- septa than the other are common and are usually indicative of contortion or genicula- tion of the corallite. In the attached apical portion of one species, the alar septa, though presumably tending to be inserted AMPLEXOID CORALS FROM ILLINOIS AND ARKANSAS 627 in normal sequence, are not observable until after a counter-lateral septum appears, their actual presence apparently being indicated, however, by slight internal swelling of the epitheca (pi. 86, fig. 2a). Further study of sections in the same sequence bears out the observation that the arrangement of septa is independent of the effects of attachment, for the plane of attachment cuts across the plan of septal arrangement without their being any adjustment of the center of sym- metry. ACKNOWLEDGMENTS The writer is indebted to Carey Croneis of Walker Museum, University of Chicago, and R. C. Moore of the University of Kansas, for lending specimens used in this study. Some locality data were furnished by J. Marvin Weller. systematic descriptions Phylum Coelenterata Class Anthozoa Order Tetracoralla Family Hapsiphyllidae Genus Amplexus of authors Diagnosis. — Simple, conico-cylindrical, rugose corals with broad generally complete tabulae; septa more or less radial in arrange- ment, extending to the axis over the upper surfaces of most tabulae, but extending distally from each tabula a progressively shorter distance as the axis is approached; dissepiments and columellar structure ab- sent. Occurrence. — Silurian to Permian of many parts of the world. Remarks. — Amplexus (sensu stricto) was founded upon A. coralloides by Sowerby in 1814, but since that time a wide variety of species has been referred to this genus on the basis of their simple structure. Type ma- terial of A. coralloides has never been sec- tioned in early stages, hence, the morphol- ogy of the genotype is inadequately known. Paleontologists now seem to be generally agreed that corals of simple structure similar to A. coralloides may very well belong to some genus other than Amplexus, but onto- gentic studies still largely remain to be done before polyphyletic relationships of 'Am- plexus" can be demonstrated satisfactorily. . Amplexus adnatus Easton, n. sp. Plate 85, figure 9; plate 87, figures 1-7 Externals. — Ceratoid to trochoid genicu- late corals with apical angle usually about 2Q°; epitheca with numerous rather fine encircling wrinkles, prominent septal grooves and interseptal ridges which always origi- nate in connection with a pair of adjacent septa; spines commonly extending from one side, especially near apical end, parracidal increase common, with new calyx starting from some eccentric position and with epitheca commonly grown over old calyx. Average length about 20 mm. with range from about 10 to 30 mm.; average diameter about 6 mm., but flared specimens may be 11 mm. in diameter at calyces. Transverse sections. — Septa not numerous, mostly reaching center, even in late stages. (See "ontogeny" for details.) Longitudinal section. — Tabulae nearly all complete, with little or no axial sag, rela- tively abruptly recurved proximally near peripheries. Occurrence. — Abundant in the Golconda formation in the Vienna quadrangle. Col- lected by Stuart Weller from his locality W- 312, which may be the E±, NW£, sec. 28, T. 13 S., R. 3 E., near top of the bluff on the high point of land between two creeks A\ miles south-southeast of Vienna, Illinois; also occurring in the Paint Creek formation. Material. — Holotype, No. 47248; para- types and topotypes, not numbered; all in Walker Museum, University of Chicago. Ideotypes, Walker Museum No. 47249, Illinois State Geological Survey No. 3537. Ontogeny. — The earliest stage observed (pi. 87, fig. la) has an axial septum which consists of the fused cardinal septum and counter septum. In the next observed stage (fig. lb) both alar septa are present, of which the left is the thicker and has migrated far- ther from the cardinal septum, therefore, it probably was inserted before the right alar. Other stages were not observed before that in which the left cardinal quadrant contains one metaseptum, the right cardinal quadrant none, the left counter quadrant the probable counter-lateral septum, and the right coun- ter quadrant one metaseptum and the counter-lateral septum (fig. lc). This asym- metrical arrangement presumably is a mani- festation of geniculation of the corallite. 628 WM. H. EASTON Next (fig. Id) each cardinal quadrant con- tains one metaseptum and each counter quadrant contains two metasepta. It will be noticed that the metasepta of the left counter quadrant are aberrant in that they lean toward the alar septum and that some of them may not reach the axis (figs, lc— If). Traces of tabulae can be observed in the last mentioned stage (fig. If), and the alar pseudofossula is developed only on the right side of the coral. The right alar pseudo- fossula still persists when 14 major septa are present (fig. 2), and each cardinal quadrant has one well developed metaseptum at- tached to the cardinal septum. The cardinal fossula soon becomes apparent but the alar pseudofossulae are represented only by slightly wider loculi than occur elsewhere; the cardinal quadrants each contain two metasepta and the counter quadrants three or four (fig. 3). When 16 major septa have been inserted (fig. 4), there are three meta- septa in each cardinal quadrant and three or four septa in each counter quadrant, but several septa have retreated a short distance from the axis. At full maturity (fig. 5) there are 22 major septa, of which three are in each cardinal quadrant and six in each counter quadrant, thus, the counter quadrants are accelerated by the time ma- turity is reached. Amplexoid retreat is very poorly shown, inasmuch as those septa which do not reach the axis are either fused near their axial edges, or else lean against a neighboring metaseptum. The amplexoid condition is developed by middle maturity, nevertheless, as shown by a section just below a tabula (fig. 7). Comparison. — This species can be distin- guished externally from the other species of Amplexus by the small size of the corallites, their contorted shape, nearly cylindrical mature portions, calical method of increase, occasional development of spines on one side, about twice as many septal grooves as septa, and by the insertion of two adjacent septa as a pair. Remarks. — Septal notation was verified through study of the septal grooves wherever possible. In this regard, it was observed that although minor septa are nowhere de- veloped, a septal groove usually occurs be- tween major septa, hence there are usually about twice as many septal, grooves as septa. Ontogenetically, this species is charac- terized by the slow rate of insertion of major septa, by marked acceleration of the counter quadrants in mature stages, and by very poorly developed amplexoid retreat. Phylogenetic relationships are with the so-called "zaphrentid" types, except that the fossulae are poorly developed and pri- mary septa tend to remain fused axially. A. adnatus appears to be closely related to A . geniculatus. Apical portions of most corallites are so contorted and spinose that study of epithecal ornament is unsatisfactory, however, it was noted in some specimens that the cardinal position is on the convex side of the corallite. It is not known how general this may be, for the cardinal position was also observed to be on some other side in a few specimens. Wherever observed, the corals were at- tached by spines to a fragment of a fenestel- lid bryozoan. One coral has two distinct and separate patches of spines and is geniculate in such a manner as to suggested that the animal originally was recumbent along a bryozoan frond and then altered its direc- tion of growth in order to make the corallite vertical, but the bryozoan frond either broke or its position was changed so that the coral was again recumbent and sent out spines. Amplexus dilatatus Easton, n. sp. Plate 85, figure 10; plate 86, figures 4, 5 Caninia n. sp. Weller, 1920, Illinois Geol. Survey, Bull. 41, pp. 170, 173. Externals. — Curved ceratoid corals; epi- theca nearly smooth with encircling wrinkles, relatively faint septal grooves and inter- septal ridges, occasionally with sparse spines; calyx rather deep, vertically walled; calical increase observed, with epitheca grown over old calyx. Mature specimens about 3 cm. long; diameter of calyx about 10 mm. Transverse sections. — 'Mature section of holotype (pi. 86, fig. 4b) has 27 major septa extending about half the radius, of about equal strength but cardinal and coun- ter septa are slightly longer than other major septa; minor septa short or rudimentary. In early maturity (fig. 4a) holotype has 19 major septa; cardinal septum short; metasepta of cardinal quadrants pinnately arranged ; alar septa almost reach axis; septa AMPLEXOID CORALS FROM ILLINOIS AND ARKANSAS 629 of counter quadrants somewhat dilated, three grouped in palmate bunches on either side of long counter septum; minor septa rudimentary. At slightly earlier stage (fig. 5) in a para- type, septa of counter quadrants much di- lated; septa of cardinal quadrants thin, sinuous. Longitudinal section. — Not prepared. Occurrence. — All specimens are from thin limestone lenses in Paint Creek shale about 10 to 15 feet below the Cypress sandstone, on the south bluffs at Indian Point over- looking the valley of Cache River, in sec. 32, T. 13 S., R. 3 E., Johnson County, Illinois. Material. — -Specimens studied, 3; holo- type, no. 47247; figured paratypes, not numbered; all in Walker Museum, Uni- versity of Chicago, collected by Stuart Weller. Ontogeny. — 'Early stages not preserved. Comparison. — This species differs from the other Chester amplexoid corals in having the septa of the counter quadrants dilated in early maturity, and in having relatively strong development of minor septa. The species can be identified externally by its curved conical shape, sparse spines, and common occurrence of the cardinal posi- tion on the convex side of the corallite. Remarks. — A. dilatatus has typical so- called "zaphrentid" type of septal pattern. It appears to be related to A. rockfordensis from the Rockford beds (Kinderhook) of Indiana. Amplexus expansus Easton, n. sp. Plate 85, figure 8; plate 86, figures 1-3 Externals. — Ceratoid, slightly curved with apical angle about 30°; epitheca generally with fine encircling striae distally but with septal grooves and interseptal ridges proxi- mally, wrinkled throughout; apical end re- curved, commonly much less flared than rest of coral, with very fine encircling striae, flattened on one side (cardinal side wherever observed) where apparently attached to foreign body; sections reveal rather deep calyx (about § length of corallite) vertically walled and lined with septa. Specimens range in length from about 1.5 cm. to 3.5 cm.; diameter of calyx about 12 mm.; early attached portion from 2 to 4 mm. long. Transverse sections. — Septa become am- plexoid rapidly, beginning their retreat at stage of about 17 septa. (See "ontogeny" for details.) Longitudinal section. — Tubulae nearly all complete, about 8 in 1 cm., recurved proxi- mally near peripheries and with proximal sag in axial region. Occurrence. — Fayetteville shale, 6 miles east and 1.5 miles north of Vinita, Okla- homa. Collected by Maurice Wallace and Arthur Bowsher. Material. — Specimens studied, 37; holo- type, figured paratypes, unfigured para- types, and topotypes, not numbered; all in the collections of the University of Kansas. Ontogeny. — Most of the septa are inserted Explanation of Plate 85 Figs. 7 — Amplexus geniculatus Worthen. Side view; holotype; XI; Illinois State Geological Survey (Worthen collection) No. 2566a. (p. 630) 8 — Amplexus expansus Easton, n. sp. Side view; para type; XI; University of Kansas, (p. 629) 9 — Amplexus adnatus Easton, n. sp. Side view; holotype; XI; Walker Museum No. 47248. (p. 627) 10 — Amplexus dilatatus Easton, n. sp. Side view; holotype; XI; Walker Museum No. 47247. (p. 628) 630 WM. H. EASTON in the very early unflared portion of the corallites (pi. 86, figs, la-lh, 2a-2h). Al- though not actually observed, the earliest stage presumably is aseptate. The earliest observed stage (fig. la) has an axial septum extending across the center of the thecarium consisting of the fused cardinal septum and counter septum. In every observed instance, the cardinal septum is more or less normal to the plane of attachment of the corallite. At the next stage (fig. 2a) the left counter- lateral septum is inserted but this apparent- ly unorthodox sequence is caused by the alar septa being crowded against the epitheca parallel with the plane of attachment and only faintly observable in sections; they are first clearly seen at the next stage (fig. 2b) which has an axial septum, counter-lateral septa, and the fully developed alar septa starting to become separate from the epi- theca. The coral grows larger (fig. 2c) and eventually adds a metaseptum in the left counter quadrant (fig. 2d) and then another in the right counter quadrant (fig. 2e). This corresponds to about the same stage shown in figure lb, but the latter specimen is aber- rant in having the center of symmetry offset toward the counter position. There may be a tendency after this stage for the septa to retreat from the axis (figs, lc— If), but even though this occurs, the septa may reverse the trend (figs, lg-li) before beginning their final retreat (fig. lj) and attaining maturity (fig. 2i). After two metasepta have been in- serted along with the alar septa, a meta- septum appears in the left cardinal quadrant (fig. lc) and then another in the right cardi- nal quadrant (fig. 2f). When each counter quadrant has four septa, and the cardinal quadrants each have two metasepta, the final septal retreat (fig. li) starts by axial thinning of septa. Alar septa and the counter septum are longer than other major septa and the cardinal septum soon becomes quite short (fig. lj), but in maturity (fig. 2i) the alar septa and the cardinal septum are shorter than the others and the counter septum is the same length as the neighboring metasepta. Comparison. — This species is readily iden- tified externally by the flaring corallites and by the brephic stage in which the epitheca is equipped with very fine encircling striae and bears the flattened area where it was attached to some foreign object (patterns of costate brachiopod shells were commonly observed). These features serve to distin- guish A. expansus from other Chester amplexoid corals. Remarks. — Ontogenetically, this species is characterized by early and rapid retreat of the major septa, by insertion of about half the total number of major septa before notable flaring of the calyx begins, by nearly radial arrangement of septa in late stages, and by nearly uniform thickness of major septa in late stages. Phylogenetic relationship is with the so- called "zaphrentid" types but the species is clearly of different ancestry than the other Chester "Amplexus." Amplexus geniculatus Worthen Plate 85, figure 7; plate 87, figures 8-14 Amplexus geniculatus Worthen, 1890, Illinois Geol. Survey, vol. 8, p. 82, pi. 10, figs. 7, 7a. Externals. — Large simple corals, common- ly geniculate near apical end and oc- casionally contorted in cylindrical portion; calyx rather deep, nearly vertically walled; epitheca occasionally spinose but always with very prominent septal grooves and interseptal ridges; corallites commonly cera- toid to trochoid near apical end, with abrupt change to nearly cylindrical shape, or gradually expanding. Average length about Explanation of Plate 86 Figs. 1-3 — Amplexus expansus Easton, n. sp.; paratypes; University of Kansas collections; X5. la-j — Transverse serial sections; reversed; 1 specimen. 2a-i — Transverse serial sections; reversed; 1 specimen. 3 — Longitudinal section. (p. 629) 4-5 — Amplexus dilatatus Easton, n. sp.; Walker Museum collections; X5. 4a-b — Transverse sections; holotype; No. 47247. 5 — Transverse section; reversed; paratype. (p. 628) Journal of Paleontology, Vol. 19 Plate 86 CT I CT I la CT CT CT c lb CT I If I Id C CT L A A— c '9 J Ih c c CT c ■CL CT I CT 2a CL 2b CL cw imsS Pk' |*\ A C 2d CL CT I /CL v I c 2e Easton — Chester Corals Journal of Paleontology, Vol. 19 Plate 87 CT C(T CL CT /CL CL CT CL CL CT CL CL CT c 9 .Q- j& #. -Qk.® Easton — Chester Corals AMP LEX 0 ID CORALS FROM ILLINOIS AND ARKANSAS 631 4.5 cm.; average diameter at calyx about 9 mm. Transverse sections. — -Septa thin, relative- ly lew in number, generally meet at axis; tabular intersections common, straight. (See "Ontogeny" for details.) Longitudinal section. — Tabulae about 4 mm. apart, highly arched distally, the pe- ripheral edges sloping proximally from counter to cardinal position. Occurrence. — The type locality was origi- nally given as "Chester limestone, Pope County, Illinois," but subsequent studies have shown the species to be restricted to the Shetlerville member of the Renault lime- stone of Lower Chester age. Material. — Specimens studied, 62; holo- type, Illinois State Geological Survey (Worthen collection) No. 2566a; paratype, same collection, No. 2566b; figured plesio- types, Illinois State Geological Survey No. 3526-3531, 3536, and University of Illinois No. X-1479; unfigured plesiotypes, Illinois State Geological Survey Nos. 3532-3535. The writer has studied Illinois specimens from the grey-green shale cropping out on the east bank of the ravine above the old Bean and Mc Master's quarry near Shetler- ville; from f mile south of Eichorn; from Melcher Hill in Hardin County; and from the ravine east of Shetlerville. Ontogeny. — Before any septa are inserted (pi. 87, fig. 8a) there is simply a ring of epi- theca. Presumably septa are inserted in an orderly manner as in the other species studied, in which case the axial septum ex- tended across the thecarium, then the left alar, right alar and left counter-lateral septa were inserted (fig. 8b) but these stages have not been observed. The alar septa migrate toward the counter septum until they stand at right angles with the axial septum, by which time the right counter-lateral septum has appeared (fig. 8c). The next observed stage (fig. 8d) shows one metaseptum in each cardinal quadrant and one metaseptum and the counter-lateral septum in the left counter quadrant and the counter-lateral in the right counter quadrant. These relation- ships persist a short time (through fig. 8e). but in the next section (fig. 10) each quadrant has one metaseptum in addition to a counter-lateral septum, and tabulae occur. Subsequently, acceleration of the counter quadrants occurs and they contain four or five septa while the cardinal quadrants con- tain two or three metasepta (fig. 11). By this stage most of the metasepta are with- drawn from the axis, although they have shown an impersistent tendency to retreat since an early stage (fig. 8c). Moreover, the epitheca is lined with septal grooves between major septa, but this suggestion of minor septa is probably misleading because the grooves seem to correspond with longitudi- nal wrinkles inside the thecarium, rather than to actual rudimentary minor septa. Later, rudimentary minor septa are defi- nitely present. At full maturity, the septa are usually about 20 to 24 in number and occur in many different patterns, varying between a radial arrangement in which most septa nearly or quite reach the axis (fig. 14) and the typical amplexoid pattern (fig. 12) in which the septa are withdrawn toward the periphery and do not extend vertically throughout their length between adjacent tabulae. An intermediate pattern (fig. 13) is obtained if the plane of a section passes just below a tabula. Explanation of Plate 87 Figs. 1, 6, 13 — Amplexus adnatus Easton, n. sp.; paratypes; Walker Museum collections; X5. la-f — 7, Transverse serial sections; reversed; 1 specimen. 2-4 — Transverse sections; reversed; 3 specimens. 5-13 — Transverse sections; 2 specimens. 6 — Longitudinal section. 7 — Trans- verse section just below a tabula. (p. 627) 8-12, 14 — Amplexus geniculatus Worthen; plesiotypes; Illinois State Geological Survey collec- tion, except fig. 13; X5. 8a-e — Transverse serial sections; reversed; 1 individual; No. 3526. 9 — Longitudinal section in cardinal-counter plane; No. 3527. 10-12 — Transverse section; reversed; 3 specimens; Nos. 3528, 3529, 3530. 13 — Transverse section; No. 3526. 14 — Trans- verse section, reversed; University of Illinois No. X-1479. (p. 630) 632 WM. H. EASTON Remarks. — Ontogenetically, this species is characterized by the marked acceleration of the counter quadrants and by the slow in- sertion of metasepta after very early ma- turity. Phylogenetic relationships are clearly with the so-called "zaphrentid" types, and A. geniculatus appears to be closely related to A. adnatus. This species is readily identified externally by the large, long, slender corallites which may be geniculate and sparsely spinose and almost always show interseptal ridges and septal grooves. REFERENCES Easton, W. H., 1945, Kinkaid corals from Illi- nois: Jour. Paleontology, vol. 19, no. 4, pp. 383-389. Grove, B. H., 1934, Studies in Paleozoic corals: Am. Midland Naturalist, vol. 15, no. 2, pp. 97- 137. Hill, D., 1935, British terminology for rugose corals: Geol. Mag., vol. 72, no. 11, pp. 481-519. Manuscript received June 9, 1944.