102 F. A. BATHER, GEINOIDEA OF GOTLAND. 



at all events until it Jims been properry described, and not take it, as Mr. S: A. Millek 

 has done, for the type-species of the genus. H. cylindricus is not niuch better, but it is 

 clear from the rigures and description that this species is not a Dendrocrinus; in fact the 

 only other genus it might eonceivably belong to is Botryocrinus, but from all species of 

 that genus it differs iu the shape of the cup, the proportions of the radials and the 

 structure of the colurnn. It is therefore quite possible to regard this as the type-species 

 of the genus, although it does not show every single generic character. That Hall did 

 not comprehend his OAvn genus is shown by the fact that in 1859 (<>j>. <-it.) he merged 

 both Dendrocrinus and Hörnornans in Poteriocrinus. 1 ) In 1861, however, lie re-asserted 

 the validity of Homocrinus and described two new species, viz., //. scoparius (op. cit., 

 p. 102, Pl. I, tigs. 1—9) and H. proboscidialis (op. cit, p. 138, Pl. LXXXV, tigs. 24 

 and 25). There can be little doubt but that the former species is congeneric with H. 

 cylindricus; since it shows the generic characters clearly it has been taken by Wachsmutb 

 and Springkk as the type-species of the genus; this, however, is an unnecessary proceeding 

 and one that would alter the date of the genus from 1852 to 1861, thus pre-dating the 

 na me by Eichwald's 2 ) application of it to Hoplocrinus dipentas, a consequence that 

 Wachsmuth and Springer seem to have overlooked. As for H. proboscidialis, on the 

 other hand, it is b} - no means obvious to what genus it belongs; and any doubts that 

 may arise as to the propriety of referring it to Homocrinus will not be dispelled by 

 Hall's statement that it »differs in the arrangement of the plates of the body» from H. 

 scoparius. 



Wachsmuth and »Springer have always maintained this genus and have clearly 

 pointed ont its difterences from Poteriocrinus, Barisocrinus, and Dendrocrinus. They do 

 not, however, seem to have altogether understood the characters by which it is separated 

 from Botryocrinus; consequently they have referred to Homocrinus many species which 

 would be more nttingly placed elsewhere. They have also, for reasons that are not ap- 

 parent, referred to this genus one or two species that have quite a different arrangement 

 of plates in the dorsal cup. To clear away these misconceptions, I take the only two 

 species that have shown the generic characters at all clearly, and base on thcm the 

 lollowing — 



Emended generic diagnosis. 



IB 5, pentagonal. BB 5, 3 bexagonal, post. B and r. post. B. heptagonal. RR 5, 

 shield-shaped; r. post. R with lower angle truncate, and resting on r. post. B; articular 

 facet straight or very sligthly curved, occupies most of the upper side of the radial. R 

 roughly lozenge-shaped, rests on post. B and r. post. B, supports x and r. ]>ost. R; its 

 right sides are often curved. Anal x six-sided, rests on post. B and R', abuts on adjaeent 



') This fact is given on the authority of Wachsmuth and Spiunger (Rev. I, 7 7). The Corrected List 

 referred to appears to be that in Rep. N. Y. State Cab. Nat. Hist. 1859; but on p. 82 of the copy in the 

 British Museum (Nat. Hist.), Homocrinus cylindricus and //. parvus stånd without alteration. 



The date 18(31 for Paheont. N. Y., vol. III, is also given on the same authoritv. The date on the title- 

 page is 1859: but the voluine is not referred to in Carus and ENGELMANN Bibliotheca Zoologien», 1861. 



2 ) Lethasa Rossica, Lieferung V, p. 58.'5, 1859. 



