158 SMITHSONIAN INSTITUTION 



the discussion of the genus. The species is represented by a single specimen, 



and that not very complete. 



Type. In the Riks Museum, Stockholm. 



Horizon and locality. Silurian, Wenlock Group, horizon /; Gotland, Sweden. 



Calpiocrinus fimbriatus Angelin 

 Plate VIII, figs. 1-5 



Calpiocrinus fimbriatus Angelin, Icon. Crin. Sueciae, 1878, p. 12, pi. 29, figs. 77, 77a, b. — Wachsmuth and 

 Springer, Revision Palaeocrinoidea, pt. 1, 1879, p. 39. — Springer, Jour. Geology, XIV, 1906, pi. 7, 

 figs. 1, 2. 



Type of the genus. 



Larger than any other species. Crown ellipsoid, widest about the upper 

 IIIBr, and with broad base; height to width at upper IIBr about 1 to 1.5 ; spread 

 of calyx from base to I Ax, 1 to 1.7. Plates convex, and arms rounded. Surface 

 smooth. Maximum crown, 33 mm. high by 23 mm. wide; base, 6 mm. 



IBB large and prominent, forming a broad, truncate base, overlapping BB 

 except small points and the truncate apex of post. B. Rays divide a second time 

 on IIBr 3 or 4 into equal branches; first ramule on inner arm usually from 

 4th IIIBr, and on outer from 6th; ramules above these at intervals of about 

 6 or 7 Br; arms diminishing by steps for about three ramules to equal final 

 branches, where they infold. Anal x large, followed by two or more plates in 

 single series ; iBr areas like the anal, but not quite so wide ; illBr usually present, 

 1 to 5 small plates in vertical series. Column extremely large, from a third to 

 two-fifths the greatest diameter of calyx; round, composed of very large, 

 rounded columnals about half as long as wide, not alternating or diminishing in 

 width. 



This species is the typical Calpiocrinus as now defined, having. 20 equal arm branches 

 bearing lateral ramules to the inside of the dichotom. The ramules do not branch again so 

 far as observed, but might do so ; they have the form of regular arm divisions, closely abutting 

 upon the main ramus and more than half its width. By reason of the successive bifurcations 

 the rami diminish rapidly in size, while the ramules taper gradually, until the branches be- 

 come equal. Angelin founded the species upon two very good specimens of which I give 

 new and accurate figures. Another fine specimen, with part of the very robust stem attached, 

 has since been obtained in Gotland (PI. VIII, figs. $a-b) ; it is the largest example of the genus 

 yet found. I have also referred to this species a fragmentary calyx figured by Angelin as 

 C. heterodactylus (PL VIII, figs. 4a, b), which seems to be more like this in the spread of 

 calyx and number of interbrachials. These are all the specimens known. 



Type. Angelin's originals, and the other specimen now first figured, are all in the Riks 

 Museum, Stockholm. 



Horizon and locality. Silurian, Wenlock Group, horizon /; Gotland, Sweden. 



