IN THE MORPHOLOGY OP THE CYSTIDEA. 15 



(Pi. I. fig. 7), but for tlie intercalation of an interradial plate 

 (18) within the radial ring. Beyrich was inclined to refer 

 Hypocrinus to the Cystids, chieily, it would seem, on account of 

 this character, and his example has been very generally followed. 

 But it is altogether unlike the other Carboniferous Cyatids, and 

 I cannot help suspecting that it is really a Crinoid, allied to 

 Lecytliiocrinus, White *. The type-specimen of this genus, 

 which was found in the Upper Coal Measures of Kansas, has 

 three infrabasals, two of which are double plates, just as in 

 Hupocrinus ; and above these are five basals and five radials, the 

 latter being bent inwards, somewhat as in Hypocrinus, and 

 bearing small facets for the arms. In this species, L. olliculce- 

 formis, there is no trace of an anal aperture in the dorsal cup, 

 and it would seem, therefore, to have been situated in the disk 

 above. But in the unique L. Adamsi, Wortlien t, from the lower 

 Coal Measures o£ Illinois, which has five infrabasals, there is a 

 circular opening between the summit of one basal and the lower 

 angles of the two radials above it. Worthen described this as 

 filled with stonjf matter, and left it an open question whether it 

 is " an anal opening or an accidental break in the test of the 

 body." The analogy of Hypocrhms would seem to indicate that 

 this is an anal opening, and that L. Adamsi should be referred to 

 this genus and not placed with L. ollicidaformis, in which the 

 anus does not open within the dorsal cup. The latter is also the 

 case in the Deyonian genus Codiacrinus, Schultze, which likewise 

 has three infrabasals, five basals, and five radials, all in contact ; 

 and except in the characters of the arm-facets, there is no struc- 

 tural difference between LecyiMocrinus, as defined by White, and 

 Schultze's type. Wachsmuth and Springer have noticed this 

 resemblance % ; but they say nothing about Worthen's remark 

 as to the possibility of the anus piercing the dorsal cup of L. 

 Adamsi. Should this really be the case, this species can hardly be 

 referred to White's genus ; while, except in the number of infra- 

 basals, it would much resemble Hypocrinus, to which Wachsmuth 

 and Springer make no reference in the text of the 'Eevision,' 

 though the name appears in the index. They might have known 



* '•' Descriptions of New Species of Carboniferous Invertebrate Fossils," Proc. 

 U.S. Nat. Mus. 1880, vol. ii. p. 256, pi. i. figs. 4, 5. 



t Geol. Survey of Illinois, vol. vii. 1883, p. 317, pi. xxx. fig. 8. 



\ " Eevision of the Palffiocrinoidea. — Part III. Sect. 2," Proc. Acad. Nat. 

 Sci. Philad. 1886, p. 152. 



