268 Field Columbian Museum — Geology, Vol. II. 



right anterior, and perhaps anterior, are compound, — the first two 

 bisected transversely, and the last, if at all, obliquely. No anal plate 

 in the dorsal cup, but the lower segment of the right posterior radial 

 probably is the radianal. Radial facets shallow, concave, filling the 

 greater part, but not all, of the distal face of the radials. Arms simple, 

 non-pinnulate. Tegmen unknown. 



This genus belongs to a little group of irregular, Inadunate Cri- 

 noids, represented by Pisocrinus in the Silurian, and Triacrinus, 

 Haplocrinus and Calycanthocrinus in the Devonian, having a mono- 

 cyclic base, and one or more compound radials divided by trans- 

 verse bisection. They belong to the group called Larviformia by 

 Wachsmuth and Springer, Larvata by Jaekel, and Monocyclica Inad- 

 unata by Bather. Our genus differs from Pisocrinus, Triacrinus, 

 and Haplocrinus in the character of the radial facets, which, instead 

 of occupying a small, squarely mortised socket in the middle of the 

 plate, are broad, shallow, and fill a large part of the distal face of 

 the radial. This alone, and there are others beside, is a good generic 

 distinction. Calycanthocrinus has somewhat similar radial facets, 

 but represents a modification on another line, having several small 

 supplementary arm-bearing radials in addition to the regular five, 

 perhaps produced by a vertical bisection at the corners of the larger 

 radials. 



The genus Phimocrinus Schultze, from the Devonian of the Eifel, 

 and elsewhere in Europe, is perhaps the one with which the most 

 interesting comparison may be made. It is of similar elevated form, 

 with five elongate basals, and five elongate, arm-bearing radials, 

 which, as defined by Schultze, are regular in form.* The genus has 

 been classed with the Symbathocrinidae. In 1882, M. D. Oehlertf 

 described and figured from the Lower Devonian of Sable, Depart- 

 ment of La Sarthe, a new species, Phimocrinus jouberti, having 

 the regular five basals, and five equal radials of the genus. 

 But in the description the author states that he observed, on 

 the two radials to the right of the anal side, and the second radial 

 to the left of it, (i. e., the r. post., r. ant., and 1. ant. RR), and at 

 about two thirds of their height, a light and very distinct transverse 

 groove, dividing these plates into two unequal parts; and he ex- 

 presses the opinion that this groove marks the anchylosis of two 

 pieces which were separate in the young stage. These transverse 

 marks are faintly shown on Oehlert's figures (PI. VIII, Fig. 1, ia, 

 ib) ; but there are in the collection of the senior author, two speci- 



* Mon. Echin. d. Eifler. Kalks., p. 29. 



t Bii'.i. Sor. (reol. de France. ,ime ser. t. X, p. 353. 



