KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:<> 2. 99 



articular facet alone. Subsequent ossicles are slightly longer t han wide, laterally com- 

 pressed, with a deep ventral groove, and apparently with no distinct axial canal. (Fig. 136). 



It appears that in each axil-arm the hrst pinnule is given off on the adanal side 

 of the hrst ossiele after the axillarv; while in 1. ant. arm it is on the adanal side of the 

 second ossiele. Since a pinnule is undoubtedly homologous with an armlet, it follows 

 that this type of arra-branching is of a different origin to that which obtains in the other 

 Gotland species. 



Ornament: if there ever was any, no traces remain. 



Stem: The average height of the ossicles in the part preserved is 0.6 mm., their 

 diameter is 6 mm.; but they alternate slightly in both height and width. There is a 

 gentle sagittal curve, and the ossicles are also rather higher on the outer curve of the 

 stem than on the inner side next the pendent crown. The articular surface of each ossiele 

 is radially striated towards the circumference. The axial canal is pentagonal; its diameter 

 is 1.75 mm.; traces of sutures are given off from its angles, which appear to be inter- 

 radial, but are slightly shifted towards the right; i. e., as seen from below, in the direc- 

 tion of the dock-hand. (Figs. 130, 137). 



Relations of the species. — Besides differing from the other European species in 

 almost everv minor detail. this species differs from all other species of ( 'aleeocrinus (sevsu 

 stricto) in the bifurcation of the 1. ant. arm, or perhaps it would be safer to say in the 

 bifurcation so low down. From all Calceocrinidae hitherto described, it differs in the 

 posession of pinnules; and, wliat is of far more importance, the plan of arm-branching 

 appears to be quite different. We can indeed hardlv suppose that this species is descended 

 from any other species of Calceocrinus. It has reached a highly developed stage, but the 

 line along which it has travelled has been one j)arellel to that on which we liave found 

 all species not only of Calceocrinus, but of Castocrinus, Euchirocrinus, and Halysiocrinus. 

 The resemblance to other Calceocrini in the anal area inay therefore be to some extent 

 homoplastic. The absolute correctness of these views cannot be determined until our 

 American friends have investigated all their species of Calceocrinida? with special reference 

 to the arm-branching. If there can be traced a distinct line of evolution leading up to 

 the present species, or if indeed all other species are found to have the normal type of 

 arm-branching, then, in either case there will have t<> be founded a new genus for 

 the reception of this species. I do not intend to suggest any name for a genus about 

 which we cannot vet be quite certain, although such a eourse is, I ain aware, far from 

 fashionable. 



Locality: Ty|>e-specimen from South Gotland, (f). Fårö, (f). Not known out of 

 Gotland. 



