j \ \ - } } , \ \ ) / 4 > i { ’ \ { i { it C ; | Nese i ‘ 1 ae - ad Universit ~ * ¥ \ t ; tol \ \ " / Y | 2 1 \ ‘ j i A } {= “ I F\ “Bomoits of the Buseum of Gampniatice Zoology sa ss AT «HARVARD COLLEGE, ae. von Or THE NORTH AMERICAN OIDEA CAMERATA. WITH EIGHTY-THREE PLATES. © 7 uted for the Museum. May, 1897. v. oe ° : MEMOIRS OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE, VOLS XT: CAMBRIDGE, U.S.A. PRINTED FOR THE MUSEUM. ; 1897. \ ; ; ; , a a oe i | Yi 7 P ri . 7 ae . - YREREU | - ae YAO LOOSE GMO GUN ii eee FEN 2OCIREN KD Joux Witsox axp Sox, Campnipcr, U.S.A. CONTENTS. THE NORTH AMERICAN CRINOIDEA CAMERATA. By Cartes WacusmutTH and Frank SPRINGER. Chapter X. Page 361 to end. dtlemoirs of the Museum of Comparative Zoology AT HARVARD COLLEGE. Vou. XXII. THE NORTH AMERICAN CRINOIDEA CAMERATA. By CHARLES WACHSMUTH ann FRANK SPRINGER. IN TWO VOLUMES WITH EIGHTY-THREE PLATES. Vou. II. CAMBRIDGE, U.S. A.: Printed for the fAuseum. May, 1897. TABLE OF CONTENTS. SYSTEMATIC PART (continued). Pace BatocriNIDAE : 361-549 Analysis of the Genera . 361 Geological and Geographical Distri- bution 363 Batocrinites . 366 Batocrinus 366 Eretmocrinus . 385 Alloprosallocrinus . 406 Eutrochocrinus 408 Dizygocrinus . 413 Lobocrinus 434 Macrocrinus 446 Dorycrinus 454 Aorocrinus 470 Barrandeocrinus . 484 Agaricocrinus 486 Acacocrinus 515 Compsocrinus 516 Periechocrinites 519 IRIAGNOOHINS >. 5 o 5 o o 5 OMe) WEIGHING 5 6 5 0 5 og 0 SOY Genneocrinus 547 ACTINOCRINIDAE j 550-641 Analysis of the Genera . 550 Geological and Geographical Distri- bution 5 byl AGHIOOWNS 5 5 co 6 5 «o 9 0 GBH Steganocrinus 578 Amphoracrinus . 586 Pace Physetocrinus 593 Cactocrinus 600 Teleiocrinus 626 SUONOCMIANS 5 6 5 5 oo 2 a CRF PLATYCRINIDAE . 642-740 Analysis of the Gener 642 Geological and Geographical Distri- bution 643 Platycrinus 647 Eucladocrinus 719 Marsupiocrinus . 730 Cordylocrinus 735 Coccocrinus . 738 HEXACRINIDAE . 741-802 Analysis of the Gone 741 Geological and Geographical Distri- utionte mune acuece elec chee eae ae, Hexacrinus 744 Arthracantha TAT Dichocrinus 753 Camptocrinus 779 Talarocrinus . 781 Pterotocrinus . 791 ACROCRINIDAE . : 803-810 Geological and Geographical Distri- bution 803 Acrocrinus 805 INDEX 813 BATOCRINIDA W. and Sp. Monocytic. THE LOWER BRACHIALS WITH WELL DEFINED INTERBRACHIALS BETWEEN THEM FORMING AN IMPORTANT PART OF THE DORSAL CUP. RADIALS IN CONTACT EXCEPT AT THE POSTERIOR SIDE, WHERE THEY ARE SEPARATED BY A HEPTAGONAL ANAL PLATE, WHICH IS FOLLOWED BY A SECOND ANAL BETWEEN TWO INTERBRACHIALS, Analysis of the Genera. I. VENTRAL DISK HIGHLY DIFFERENTIATED: THE PLATES LARGE AND HEAVY, FORMING A RIGID INTEGUMENT. ARMS NOT BRANCH- ING BEYOND THE CALYX . . .-.- - -:- += =: = A. ARMS BISERIAL; BASALS THREE. 1. ANUS AT THE END OF A TUBE. a. Interbrachials separated from interambulacrals by an arch of brachials. Calyx biturbinate. Arms short, equidistant; anal tube very long and central; respiratory pores twenty, well defined . .. - Arms long, paddle-shaped ; anal tube excen- tric; respiratory pores twenty . .- Calyx eonicell, dorsal cup almost flat, ventral disk greatly predominating in height; anal tube central ; respiratory pores (WOM; G o 6 0 oa 0 5 0 b. Interbrachials connected with patisserie Arms arranged in groups, the openings di- rected upward ; anal tube large, central. Calyx pyriform to wheel-shaped ; arms twenty ; respiratory pores not visible . Calyx elongate, biturbinate or subovoid ; arms twelve to sixteen ; respiratory pores ECU RM Ra TAM eae, ccm@ase! toy rij eo pfeniss c. Interbrachials in contact with interambulacrals at anal side only. Calyx wheel-shaped; anal tube very large, central; arms short, single or paired; re- spiratory pores twenty . - - 46 BATOCRINITES. Batocrinus. Eretmocrinus Alloprosallocrinus. Lobocrinus. Macrocrinus. Eutrochocrinus. 362 THE CRINOIDEA CAMERATA OF NORTH AMERICA. Calyx rotundate ; anal tube moderately small, about central; arm openings twelve to twenty; arms long, single or paired, often in the same species; respiratory pores not visible... . .. =. = 2. Anus WITHOUT A TUBE. a. Calyx lobed ; arms arranged in groups. Calyx more or less elongate. Arms heavy, one from each opening. Arms ten, recumbent on the dorsal cup ; pin- mules tml 6 56 56 5 50 6 6 5 Arms one only from each opening, erect, MMR IWGNAy,o o 6 59 5 6 9 9 Oo C Arms slender, paired ; upper arm joints spiniferous; posterior oral and proximal radial dome plates extended into spines . b. Calyx hemispheric or pyramidal. Dorsal cup from yery slightly convex to coneave; arms heavy. Orals and radial dome plates prominent. ... . B. ARMS UNISERIAL. 1. BaAsALs THREE. INTERBRACHIALS NOT NuMEROUS. CoL- UMN ROUND. a. Arms delicate, joints cuneate, alternately arranged, only interlocking at the tips. . . . -. . b. Arms heavy, joints quadrangular. INWOGWM 6 6 a © 6 0 6 6 5 0 0 Arms more than ten) =) eee 2. BASALS FOUR; COLUMN QUADRANGULAR. Arms slender, joints cuneate; plates deli- cate and highly ornamented. Interbrach- jals and interdistichals very numerous . 10 VENTRAL DISK COMPOSED OF SMALL, IRREGULARLY ARRANGED PLATES, WITH OR WITHOUT ORALS. ARMS GENERALLY BRANCHING TOMI WE GAAK 9g 9 6 6 0 9 0 9 5 9 9 OD A. ARMS BISERTAL FROM THE CALYX UP. 1. Basals three ; anal area wide. Calyx elongate, urn-shaped ; plates thin and elongate; arms grouped. Orals indistin- guishable. The column with large cen- iellemmls 6 5 0 5 o 0 o 8 9 9 Calyx depressed globose, plates short and heavy. Arms branching, given off in pairs, their facets contiguous; orals gen- erally represented; central canal large . Calyx low, strongly lobed at the arm regions, plates thin, highly ornamented. Arms arranged in clusters. Central canal of moderate size. . .. - Dizygocrinus. Barrandeocrinus. Aorocrinus. Doryerinus. Agaricocrinus. Acacocrinus. Habrocrinus. (?) Desmidocrinus. Compsocrinus. PERIECHOCRINITES. Periechocrinus. Megistocrinus. Genneocrinus. BATOCRINID &. 363 2. Basals four. Dorsal cup similar to that of Megistocrinus ; arms heavy, flattened on the back. . . Abacocrinus Geological and Geographical Distribution. Wumber of known species. (Open figures indicate American; those marked ( ), European.) BaTocRInDz. FORMATION. Periecl eas eriecho- Batocrinites. erinttes: G Oo . g 2 a a By 2.4 a a 3 4 EI < Qo say - | a s - | A a a i mt} | a ) American. RES |3/-2/3/2/ 8 S/2)s/218)e]8 B/S/2\|8 |2/2/ 2 BES |218/S/2/5/S/21S/S/2/8/ 8/8 lelsilsisisle Ses s|alslols! sls] elelal|s| ol] 8] Zio je) eals PA joo} S/S/F)/o/8/8] 2 1S]o]/s5/8)/e!]8 18) Si] .0 |-2)a]8 < Blelslelslsl/S12/8/8] S813 lalelle |e eis AIR ISTIBISIBIS ISIS IAS /4]/ ml Jolla [slols Warsaw. 2 5 4 |Keokuk. B42 a) i] a fm 1] 2/10 = |— 3 | = . g 1 *g |Up. Burlington. B 3/9 4/3/3)]3 2/5) 8 l (1) ° z=) a — g | |Low. Burlington. A 9/6 2) 1 3] 3)4 ff a 1) $ = peal Pe E} Kinderhook. 3 Waverly. 2 4 A} i Chouteau. @ |Hamilton. 1 9|2 2 es i) 5 Q | Up. Helderberg. |Hifel. (3) < Wenlock. 8 5 1 EI RISEN Gotland. (1) 2 1(19) 1(4) (16) (6) | 2 — L pees * | FHudson River. 2 q 153 19/19] 1 |10) 6 | 4 | 22 11/10} 22] 2 2) TT) 12)) 2 9 Total species 208 | (9) (1) |@) (a9)|(4)][f(as) ay} (6) Remarks. —The Batocrinide and Actinocrinide differ from the two preceding monocyclic families, Melocrinidze and Calyptocrinide, in having a large anal plate separating the two posterior radials and resting upon the basals; and as a consequence of this a hexagonal base, which is composed 564 THE CRINOIDEA CAMERATA OF NORTH AMERICA. in all but two of the known genera in both families of three equal plates. The orientation of these plates is uniform throughout both families, viz. : the interbasal sutures are directed toward the anal plate and the two antero-lateral radials. The anal plate in the Batocrinide is heptagonal, a and is followed by three plates in the first Sy crite ; my __ interbrachial row, viz.: a second anal and two WE D2 nee interbrachials; whereas in the Actinocrinidse 5 a Oo Shine the anal plate is hexagonal, and is followed TBO ate Oy . only by the two interbrachials, — there being : @) » no second anal. We regard the presence of wo hen DQG Gy 30) a second anal within the first row of inter- G; Us O OWS brachials as of considerable morphological im- DO OFS ~ Y Cae ; Ss GY portance. It is represented without exception ~SBS5 oe, from the Lower Silurian to the close of the Devonian in all monocyclic Camerata in which Fic. 18. Batocrinus. 3 i anal plates occur; in the Kinderhook, for 6 =basals. R=radials. «2 = special anal plate. i — supplementary anal. ir = the first time, we find both forms together: emer the Actinocrinoid with but two plates above the first anal, and the Batocrinoid with three. When there are three basals, the superior edge of the basal cup is nine- angled, six of the angles being salient, the others retreating, and the suture lines are directed to the middle of the two antero-lateral radials and the anal plate. By this arrangement two of the radials are heptagonal, and the three others hexagonal. In Compsocrinus with four basals, the posterior and anterior basals are pentangular, the two others quadrangular, the anterior radial hexangular, all others heptangular. The alternate bifurcation of the arms from the two main branches of the rays, which is characteristic of the Actinocrinide. forms another well. marked distinction between the two families, and is also very constant. Among the Batocrinide this mode of bifurcation occurs only in Gennio- crinus from the Upper Devonian, but there it goes along with a second anal; and we must regard this genus as a transition form toward the Actinocrinide. The paired arm structure also, although not a constant character, occurs only among the Batocrinidz; never among the Actino- crinide. Another significant fact, tending to confirm the separation of the two groups as distinct families, is that so far as known the Batocrinidx - disappear in Hurope with the dawn of the Carboniferous — except perhaps BATOCRINID&. 365 Megistocrinus, of which a species may possibly exist in the Mountain Lime- stone of England—and are replaced by the Actinocrinide. ‘This is also the case in the western territories of the United States. At Lake Valley, New Mexico, among many hundred Camerate Crinoids collected from the horizon of the Burlington group, we found only one or two straggling Batocrinoids. The genera for which this family is proposed, with the exception of Compsocrinus, have been heretofore referred by us and others to the Actinocrinide, and most of the species were originally described under Actinocrinus. Even the genus Batocrinus was not accepted by the earlier writers. This was no doubt largely due to the fact that Casseday in describing the genus overlooked the arrangement of the plates of the anal area, which, as we think, forms the principal distinction between the two groups. He only alluded to the meeting of the distichals and palmars over the interbrachials, and the separation of the latter from the plates of the ventral disk. The importance of the structure of the anal area was pointed out by us in the Revision, Part II., p. 139, when we recognized the genus Batocrinus, but at that time we only made it the type of a subgroup under the Actinocrinide. As now defined, the Batocrinide are by far the largest family of the Camerata, and they have a greater stratigraphic range than any except the Rhodocrinide, — appearing first in the Hudson River group of the Lower Silurian, and continuing into the Warsaw. The family consists of eighteen genera, of which twelve, so far as known, are restricted to America, and six to Europe; while Periechocrinus and Megistocrinus occur on both sides of the Atlantic. Of these genera two hundred and three good species have been recognized, — fifty of them coming from Europe and one hundred and fifty-three from North America. There are in Europe two other genera which probably ought to be placed in this family, — Polypeltes Angelin, and Spyridiocrinus Oehlert ; but as the arrangement of the two or three proximal rings of plates in the calyx cannot be made out in the specimens, they may possibly belong to the Melocrinide. We have subdivided the genera of this family into two sections, which will considerably facilitate identification, viz. :— 366 THE CRINOIDEA CAMERATA OF NORTH AMERICA. A. Those in which the ventral disk is highly differentiated, the plates being large and heavy, and in which the arms do not branch beyond a minute axillary at the arm opening . . . BATOCRINITES. B. Those in which the ventral disk is composed of small, irregu- larly arranged plates, and the arms generally branch after Weenie 56 5 5 6 5 6 6 6 0 0 6 6 oo 5 5 oo JPDIRMODICISIOOIRINNIENDS, A. BATOCRINITES. BATOCRINUS Cassepay. 1854. CassepDay; Zeitschr. der Deutsch. Geol. Gesellsch., Vol. VL, p- 237. 1857. Prete; Traité de Paléont., Vol. IV., p. 324. 1862. Dugsarprn and Huré; Hist. naturelle des Zoophytes Echinod., p. 142. 1865. Mrrx and Wortuen (Subgenus of Actizocrinus) ; Proceed. Acad. Nat. Sci. Phila., p. 153. . 1866. Merk and Wortuen (Subgenus of Actizocrinus); Geol. Rep. Illinois, Vol. I1., p. 150. 1869. Merk and Wortuen; Proceed. Acad. Nat. Sci. Phila., p. 350. 1873. Merxrx and Worrnen; Geol. Rep. Illinois, Vol. V., p. 364. 1878. W. and Sp.; Proceed. Acad. Nat. Sci. Phila., p. 329. 1879. Zitre.; Handb, der Paleontologie, Vol. I., p. 370. 1881. W. and Sp.; Revision Paleocr., Part II., p. 162 (Proceed. Acad. Nat. Sci. Phila., p. 336). 1885. Sremmann; Elemente der Paleontologie, Part I., p. 157. 1890. S.A. Mitrer; North Amer. Geol. and Palzont., p. 227. 1892. S. A. Mirren; Ady. Sheets of the 18th Geol. Rep. Indiana, p. 23. Syn. Actinocrinus (in part) Suumarp, Hatt, Waite, McCuesney, and Mrrx and Wortuen prior to 1865, QuENsTEDT as late as 1885. Syn. Uperocrinus (in part) Mrex and Wortuen, 1865; Proceed. Acad. Nat. Sci. Phila., p. 153. Calyx biturbinate to subglobose; the rays not lobed. Plates heavy, the surface more or less convex and frequently nodose, but otherwise not orna- mented. Basals three, proportionally large, forming a hexagonal cup thickened at the lower margin, and generally projecting laterally. Radials very large. Costals two, small, quite frequently anchylosed; the first qua- drangular, almost linear; the second pentangular. Distichals and palmars as large as, or larger than the costals. Palmars are always represented, except occasionally in the anterior ray. The posterior rays frequently have post-palmars, which do not occur in the other rays. Arm openings equidis- tant, directed horizontally. Respiratory pores twenty, two above each interradius, and two to each interdistichal space; placed at a somewhat higher level than the arm openings. Arms twenty to twenty-six; in species with more than twenty arms the extra number is divided between the two BATOCRINID &. 367 posterior rays. The arms are simple, very short, slightly incurving, and rounded on the back (never spatulate); the pinnules stout, deep, closely packed, and flattened at their lateral faces. Interbrachials separated from the interambulacral pieces by the overarching palmars, which form a con- tinuous series around the calyx; the four regular sides have rarely more than three, of which the first is very large, those of the second row being small, while some species have but one. The anal plate is succeeded by three large pieces, and these variously by one, two, or three interbrachial plates. There are neither interdistichals nor interpalmars. Ventral disk convex ; the plates of nearly uniform size, except the posterior oral, which is larger, more convex, and forms the base of the anal tube on the anterior side. Anal tube central, heavy and long, often reaching twice the length of the arms. Column stout, round; the axial canal small and pentangular. Distribution. — Batocrinus ranges from the Kinderhook to the lower part of the St. Louis group, and, so far as known, is restricted to America. Type of the genus: Batocrinus icosidactylus Cass. Remarks. — The genus Batocrinus was not accepted by Hall, White, or McChesney, who referred the respective species to Actinocrinus. Meek and Worthen were at first inclined to give it only subgeneric rank, but in 1873 recognized it as a full genus, in which they were followed by us in 1881. As the best distinction between Batocrinus and Actinocrinus, Casseday pointed out the closure of the fixed upper brachials over the interbrachial plates, and no doubt this isa most excellent character, and holds good in the typical species of Casseday. But unfortunately, among the species which Meek and Worthen afterwards referred to the genus, there are quite a number in which this rule does not apply, and these species, which have good generic characters of their own, have been eliminated by us, and made the types of independent genera. Batocrimus, as now restricted, differs from Hvetmo- crinus in having short cylindrical arms in place of paddle-shaped ones, and in the greater length of the anal tube. Zutrochocrinus and Dizygocrinus difter from both of them in the tendency of the arms to double from the same opening. Macrocrinus and Lobocrinus have the rays lobed and the arms arranged in groups; in the former the anal tube is large and central, in the latter short and excentric. The arms of Batocrinus are sometimes slightly flattened towards the tips, but never paddle-shaped like those of Hretmocrinus. 368 THE CRINOIDEA CAMERATA OF NORTH AMERICA. Batocrinus icosidactylus Cassepay, Plate XX VII. Figs. 3a, b, c. 1854. Batocrinus icosidactylus — Cassepay ; Zeitschr. d. Deutsch. Geol. Gesellsch., Vol. VI., p. 238, Plate 2, Figs. 1, la-c. 1857. Batocrinus icosidactylus — Pictur; Traité de Paléont., Vol. IV., p. 324, Plate 101, Fig. 6. 1867. Actinocrinus (Batocrinus) icosidactylus —M. and W.; Geol. Rep. Illinois, Vol. V., p. 367. 1881. Batocrinus icosidactylus — W. and Sv.; Revision Paleocr., Part IL., p. 166. 1885. Actinocrinus icosidactylus —QuENstEDT; Handb. der Petrefactenkunde (3te Auflage), Plate 77, HO, See icosidactyus —S. A. Muuner; Adv. Sheets Geol. Rep. Indiana, p. 24, Plate 4, Figs. 1-5. Calyx nearly as wide as high. Dorsal cup rarely more than half the height of ventral disk, low saucer-shaped, with a protuberant base; plates heavy, slightly convex, their surface smooth or obscurely granular. Basal cup projecting conspicuously beyond the level of surrounding plates, almost circular in outline; the median part deeply depressed for the recep- tion of the column; central perforation subpentangular. Radials short, partly hidden from view by the overhanging rim of the basals. First costals quadrangular, three times as wide as long, narrower than the second. Disti- chals two, a little larger than the costals. Palmars three, increasing in width upward and placed in longitudinal series, which are separated by well defined grooves. Arm openings facing laterally, forming a continuous row around the calyx. Arms four to each ray; their structure not known. Inter- brachials three (rarely four) to the interradius; the first much larger than the other two. The anal plate, which resembles the radials, is followed by three plates, and these by one or two. Interbrachials not connected with the plates of the tegmen, the higher brachials being in lateral contact. Ventral disk conical, passing gradually into a strong, almost central tube. The larger plates, as a rule, are extended into thorn-like projections, and are surrounded by smaller, slightly convex pieces. Orals quite excentric, four of them spinous, the posterior one merely convex. The radial dome plates, which are represented by plates of a first, second and third order, are also spiniferous. Anal tube long, heavy, and composed of convex pieces, among which larger thorn-like plates are scattered at intervals. Column round. Horizon and Locality. — Warsaw limestone; Spergen Hills, Ind., and Barren Co., Ky. BATOCRINID &. 369 Batocrinus irregularis Cassrepay. Plate XX VII. Figs. 4a, b, and c. 1854. Cassepay; Deutsche Geol. Gesellsch., Band VI., p. 240, Plate 2, Figs. 2a, 4, c. 1867. Mex and Wortuen; Geol. Rep. Illinois, Vol. V., p. 367. 1881. W. and Sp.; Revision Palexocr., Part II., p. 166. 1892. S.A. Mitrer; Adv. Sheets 18th Rep. Geol. Surv. Indiana, p. 26, Plate 4, Figs. 6-9. Resembling the preceding species, but readily distinguished by its smaller size, more elongate form, much greater depth of dorsal cup, by having a less number of arms, and the absence of spiniferous plates in the tegmen. Sur- face of plates smooth or slightly wrinkled, the radial ones transversely ridged ; suture lines distinct. Basal cup projecting, circular in outline, deeply excavated for the attach- ment of the column. Radials short, considerably wider than the costals. Costals small, quadrangular, twice as wide as long ; succeeded in four of the rays by 2 X 2 distichals, which resemble the costals in form and size, and support 2 X 2 X 2 fixed palmars. In the anterior ray there are two rows of three successive distichals followed by the free arms. Arms eighteen, the ambulacral openings directed horizontally. Interbrachial plates three ; the first larger, supporting two plates in the second range. The anal piece is succeeded by three plates, and one above. Tegmen high-conical, higher than the dorsal cup; composed of comparatively few, large, tumid plates. Anal tube stout, almost central; constructed of strongly nodose pieces. Arms and column unknown. Horizon and Locality. —Same as last. Batocrinus subzqualis (McCursney). Plate XXVIII. Figs. 7a, b; Sa, 6, and 9. 1860. Actinocrinus subequalis— McCuesney, Descr. Pal. Foss., p. 17. 1870. Actinocrinus subequalis —McCursney; Chicago Acad. Nat. Sci., p. 13, Plate 5, Fig. 7. 1873. Batocrinus subequalis —Merx and WortuEn; Geol. Rep. Illinois, Vol. V., p. 367. 1881. Batocrinus subequalis—W. and Sp.; (Syn. of Batocrinus discoideus), Revision Paleoer., Part II., p- 166. Syn. Actinocrinus discoideus —Ha1L; 1858, Geol. Rep. Iowa, Vol. I., Part II., p. 594. Syn. Batocrinus discoideus —MeEK and WorTHEN}; Geol. Rep. Illinois, Vol. V., p. 367, and Whit- field; Mem. Amer. Mus. Nat. Hist., 1893; Vol. I., p. 14, Plate 1, Figs. 19, 20. - Syn. Actinocrinus formosus — Hatt, 1860; Suppl. Geol. Rep. Towa, p. 30. Syn. Batocrinus formosus — Mex and WortHen; 1873; Geol. Rep. Illinois, Vol. V., p. 367. Syn. Batocrinus equabilis— 8. A. Miuuxr, 1894; Geol. Surv. Missouri, Bull. 3, p. 25, Plate 5, Figs. 18, 14, 15. 47 THE CRINOIDEA CAMERATA OF NORTH AMERICA. (Ss) a (=>) Calyx somewhat biturbinate, as wide as high. The dorsal cup larger than the ventral disk; sides expanding gradually to the arm bases and forming nearly a straight line. Plates nodose, except the first costals which are generally flat. Base more than twice as wide as high, hexangular as seen from the bottom ; the interbasal suture lines distinctly grooved; column facet deeply depressed, Radials wider than long, widest at two thirds their height, exca- vated at the upper edges. Costals small, both together very little more than half the size of the radials; the first linear; the second a little longer and wider in the upper part. Distichals two, except in the divisions facing the anal side, in which there is but one, which is axillary. Palmars 2 X 20; but while those approaching the posterior side bifurcate again, the others are followed directly by the free arms. Arm facets concave, arranged in a continuous row around the calyx. Arms twenty-two, short, almost of equal width to their tips. Pinnules closely packed together, long, deep, and flattened at the sides. Regular interbrachials consisting of one large plate, sometimes followed by one or two smaller ones; the former extending to the top of the first distichals and even to the palmars. Anal plate consider- ably higher than the radials and succeeded by three large plates, and these by a single one. Ventral disk subconical, plates tuberculose, pomted at the top. Orals and first radial dome plates larger than the intervening supple- mentary pieces, which are quite irregular in form and size. Anal tube very long, sometimes extending several inches beyond the tips of the arms; com- posed of tumid plates. Column constructed of rather large joints with rounded edges; the internodals somewhat the narrowest. Horizon and Locality. — Lower Burlington limestone; Burlington, Iowa, and in rock of the same age in Southern Missouri. Type in the (Worthen) Illinois State collection, Springfield. Remarks. — There is not the least doubt that Actinocrinus discoideus and A. formosus, both described by Hall, are identical with this species. ‘The former name has priority, but, being described from a crushed specimen, and neither the name nor the description giving a correct idea of the species, we are compelled to adopt McChesney’s name. The form described as Actino- crinus formosus differs only in the less convexity of the plates. BATOCRINID &. (Sh) I py Batocrinus equalis (HAt1r). Plate XXVILT. Figs. 5, 6. 1858.