10 



DR. P. H. CARPENTEE OlS" CEUTAIN POINTS 



Pscii doer ill us bifasciatus 



„ magnificus 



„ quad/i'ifasciatus 

 „ ohlongus 



Apiocystis pentremitoides 



,, clegans 



Lepadocrinus Gebhardi 



Interradials. 



AB missing. 

 AB missing. 

 CD missing. 

 CD missing. 

 CD missing. 

 All present. 

 All present. 



JPS, 



Fseudocrintis. 



Apiocystis. 



Lepadocrinus. 



N.B. — Pseudocrinus, as limited above, is probably a good genus ; but I have 

 my doubts as to the separation of Apiocystis from Lepiadocrinus. 



Another interesting and geologically earlier form is Lepo- 

 crinites {Lepadocrinus) Moorei of Meek*, from the Cincinnati 

 grouj) of Indiana, which, differs from L. Gehhardi iu having five 

 ambulacra and a pore-rhomb on plates 10-15, in addition to 

 those on 1-5, 12-18, and 14-15. I am inclined to regard these 

 characters as of generic A^alue, and would propose therefore to 

 distiuguish Meek's species by the name Lepadocystis. 



Callocystis is another genus presenting the same general plan 

 of structure, though I should not interpret its calyx quite in 

 tte same way as Hall f has done. Five of the eight costals which 

 he describes in the second cycle are, I believe, the true basal 

 plates, Nos. 5-9 (PI. I. fig. 5), those namely which are marked 

 5, 6, 8, 9, 11 in Hall's fi.gure ; while his plates 7, 10, and 12 

 seem to me to represent radials E, C, and B, or plates 12, 14, 

 and 10 respectively, in Echinoeoicrmus and Lepadocrinus (PI. I. 

 figs. 3, 6). They are situated lower than usual and enter the 

 basal ring, just as the posterior radials do in certain species of 

 Semicidaris and other Urchins. The anal opening would then 

 be situated between basals 7 and 8 below and a single plate 

 above, which I regard as representing radial D or plate 13 of 

 Ecliinoencrinus and Lepadocrinus (PI. I. figs. 3, 5, 6). This 

 being the case, the j)ore-rhombs of Callocystis occupy the same 

 positions as those of the above-mentioned types, viz., on plates 

 1-5, 12-18, and 14-15, though its five ambulacra and the peculiar 

 relations of its radials give it a very distinct generic position. 



* Eep. Geol. Surv. Ohio, Palseontology, vol. i. 1873, p. 39, pi, iii. fig. 4. 

 i" ' Pala?ontology of New York,' vol. ii. p. 238, pi. 1. 



