342 F. A. Bather — On Sapalocrinus Vidorice. 



difficulties of the systeroatists seem to have arisen from the fact 

 that the whole assemblage is intermediate between the older 

 representatives of Inadunata Monocyclica and the Carboniferous 

 forms of PlatycrinidEe. In the " Crinoidea of Gotland," i, p. 19/ 

 I suggested that the Camerata might have been derived from the 

 Inadunata, and that such genera as Platycrinus might " represent 

 stages in the evolution not far removed from the true Inadunate 

 type." Dr. Jaekel's criticism of this sentence is based partly ou 

 the erroneous inference that I regard Platycrinus " als den 

 Ausgangspunkt der Entwickelung der Cladocrinoideen (Camerata) " 

 (op. cit., p. 38), and partly on his own supposition that Platycrinus 

 is descended from Marsupiocrinus because the latter is older in 

 geological time. It was only by getting Coccocrinus and " Platy- 

 crinus " retiarius conveniently out of the way, and by overlooking 

 Cordylocrinus, that Dr. Jaekel could have written thus. All that is 

 known of the ontogeny and phylogeny of crinoids favours the view 

 that these and the allied genera mentioned above were derived from 

 genera with a cup composed solely of 5 BB and 5 ER, with 

 dichotomous arms clearly distinct from the cup, with the greater 

 part of the tegmen covered by five large plates, between which the 

 ambulacra passed to the mouth, and with very slight disturbance of 

 symmetry due to the anus. On the other hand, Cordylocrinus, 

 Coccocrinus, and their allies gave rise, in their turn, to the more 

 highly specialized forms, first Marsupiocrinus, and at a later date 

 Platycrinus and Eucladocrinus. 



Eevision of Cobdylocrinus and the " Hapalocrinidje." 



Before considering to which genus the Melbourne specimen is 

 most nearly related, some revision is required. 



Wachsmuth and Springer (" Monogr. N. Amer. Camerata," ii, 

 p. 735, 1897) have placed "Platycrinus" retiarius in Cordylocrinus. 

 But according to Angelin's " Iconogr. Crin. Suec," pi. xxiii, fig. 6, 

 C. comtus, the type-species, bears two pinnules on each lIBr. The 

 brachials are therefore compound, derived by fusion from biserial or 

 zigzag pairs. The same appears from Hall's figures (" Paleeont. 

 N.Y.," iii, pi. iv) to be the case with the American species which 

 Wachsmuth and Springer refer to this genus. Certainly the same 

 arm-structure obtains in the undescribed Dudley species with two 

 arms to the ray, mentioned by those authors on p. 736. In " Platy- 

 crinus " retiarius, however, the IIBr are uniserial, approaching the 

 zigzag arrangement, and each bears one pinnule. This is surely 

 enough for generic distinction. 



Dr. Jaekel calls the last-mentioned species Thallocrinus retiarius, 

 so that we must now consider the claims of the genus Thallocrinus 

 to recognition. Jaekel's family Hapalocrinidse is thus defined (op> 

 cit., p. 94) : — " Dorsal cup consists of a cii'clet of large spade-shaped 

 radials, and a tripartite (2 + 1) occasionally fused basal circlet ; 

 tfgmen essentially composed of five large orals, but sometimes 

 there are distinct suborals [interbrachials]. The five arms fork 

 1 K. Svenska Vetenskaps-Akad. Handl., Ed. xxv, No. 2. (Stockholm, 1893.) 



