KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:0 2. 103 



radials, supports two plates of anal tube. Arms dichotomous. Anal tube wide and com- 

 posed of numerous small plates. 



This genus differs from Dendrocrinus, from which it is probably descended, in the 

 different relations of r. post. K and R', for in Dendrocrinus R' retains its normal position 

 as an infer-radial. From Parisoerinus, which is one of its descendants, it differs in the 

 fa et that no plate of the tube or third anal has yet sunk into the dorsal cup. From 

 Poteriocrinus and all Scaphiocrinites it differs in this same point as well as in the absenee 

 of pinnules. From the BotryoeriniTes it differs in the simple dichotomy of its arms and 

 in the shape of anal x, which in Botryocrinus is shaped like the radials and supports 

 either one or three plates, not two. Apparently also the species of this genus may be 

 distinguished from most Botryocrinites by the presence in the lätt er of more pronounced 

 axial folding of the cup and of more horseshoe-shaped radial facets. 



Before proceeding to diagnose our Gotland species, it will be as well to run through 

 the various Species that have been rightly or wrongly referred to Homocrinus, so that 

 we may see with which it is necessary to compare it. 



alternatus, Hall {Poteriocrinus), Nat. Hist. X. Y. Palseont. vol. I, p. 83, was referred to 

 Homocrinus by Hall (op. cit., vol. II, p. 185), and was placed in Dendrocrinus 

 b}- Wachsmuth and Springer, (Revision, I, p. 76). Nothing as to the generic 

 relations can be made out from the specimen figured by Hall. 



ancilla, Hall {Dendrocrinus), Trans. Albany Inst. vol. X, p. 65; 1883; (sep. copy 1879). 

 This was referred to Homocnnus by Wachsmuth and Springer in 1886 {loc. cit.); 

 they have presumably examined the type-specimens, for there is nothing in Hall s 

 description or figure that gives :uiv elue to the genus. 



angustatus, Meek and Worthen {Homocrinus), Proc. Acad. Nat. Sci. Philadelphia, vol. for 

 1870, p. 30, has been referred to Dendrocrinus by Wachsmuth and Springer, 

 (Revision, I, p. 76). They are presumably eorrect. 



crassus, Whiteaves, (Homocrinus), Contrib. Canad. Palseont., vol. I. p. 95, 1889. This is 

 founded on a dorsal cup from the Bamilton group, which cannot be distinguished 

 from that of a Botryocrinus. The posterior side of the cup is not shown in the 

 figure: bnt Air. Whiteavks has verv kindlv sent me the type-specimen, the 

 evidence of which is quite clear. As a Botryocrinus it is doubtful whether the 

 species will stånd. 



curtus, Muller (Poteriocrinus), Verhandl. d. naturh. Verein f. Rheinlande, vol. XII, p. 80; 

 1855; in Zeiler and Wirtgen. This was referred to Parisoerinus by \Yachs- 

 mlth and Springer (Revision, I, p. llö) and there can be little doubt that the 

 reference was eorrect; why they referred it to Homocrinus in 18<S6, I cannot 



imagine. 



cylindricus, Hall {Homocrinus), Nat. Hist. N. Y. Palseont., vol. II, p. 186. The type- 

 species of the genus. It is sufheiently clear from the figures and description that 

 the plates of the cup are as in the above diagnosis, the only doubt being as to 



