1 62 SMITHSONIAN INSTITUTION 



Four species referable to this genus have been described, two from Gotland, and two 

 from America ; to these I have added a fifth and doubtful one based on Gotland specimens. 

 The species will be arranged as follows : 



The Species of Anisocrinus 

 I. Anal and iBr plates I. 



Crown ventricose at the calyx, contracting above IBr. 



IBB large, protuberant, or in projecting rim ; IIBr 3 or 4 A. interradiatus. 



IBB small, not visible in side view ; IIBr 2 A. angelini. 



Crown obconic below, gradually expanding beyond IBr. 



IBB large, in conical ring continuous with column A. greenei. 



II. Anal and iBr plates more than one. 



Crown obconic below, gradually expanding. 



IBB visible, not forming rim A. oszvegoensis. 



A doubtful species, variant from the genus, with arms heterotomous 



and no radianal ; otherwise like A. interradiatus ( ?) A. irregularis. 



Anisocrinus interradiatus Aneelin 



.-i v 



Plate X, figs, 1-3& 



Anisocrinus interradiatus Angelin, Icon. Crin. Suec, 1878, p. 13, pi. 22, figs. 18, 18a.— Wachsmuth and 

 Springer, Revision Palaeocrinoidea, pt. 1, 1879, p. 37. — Springer, Jour. Geology, XIV, 1906, pi. 6, 

 fig- 9- 



Type of the genus. 



A small species. Crown ventricose at the calyx, obconic below, contracting 

 and cylindrical above IBr, and squarely truncate at the top — the arms forming 

 a parallel bundle, and squarely infolding about the first to fourth IVBr. Great- 

 est width about the first IBr; height to width at RR, 1 to 2; spread of calyx 

 from base to RR, 1 to 3.5; base obconic, truncate. Surface probably smooth. 

 Maximum crown, 15 mm. high by 11 mm. wide; base, 3 mm. 



IBB of good size, protuberant in small conical ring or projecting rim. 

 BB large. RA large, located below r. post. R, usually but not always touching 

 r. ant. R. Anal x very large, acuminate, rising to height of second or third IIBr. 

 iBr not quite so large as. v. RR larger than BB. IBr short and narrow. Height 

 of B to R to IBr, 3 :3-5 : 1. IIBr 3 or 4, half as high as wide; IIIBr 6 to 8, fol- 

 lowed by one bifurcation. Arms closely abutting, evenly rounded, tapering but 

 little ; dividing into equal bifurcations each about half the width of the preceding 

 branch, sometimes unequal. Column unknown. 



Angelin's figure did not show the radianal, but it is perfectly developed in the type 

 specimen, and also in two others since found (PI. X, figs. 2b, 3Z7) ; the last of these specimens 

 shows the arms to their full height, which the type did not. All the specimens are apparently 

 smooth. 



Type. Angelin's original and the other specimens figured herein are in the Riks Museum, 

 Stockholm, Sweden. 



Horizon and locality. Silurian, Wenlock Group, horizon f ; Wisby, Island of Gotland. 



