364 PROCEEDINGS OF THE ACADEMY OF [1879. 



port of the arms. The brachials abut laterally, leaving no space 

 for interradial or anal plates ; the hinge line constructed as in 

 Eupachycrinus. 



Arras two to each ray, strong, and, so far as j^et observed, com- 

 posed of a single series of transversely oblong pieces. 



Column round or obscurely pentagonal. 



Geological position, etc. The typical form of this genus has 

 been found only in America, where it is restricted to the Burling- 

 ton limestone and Coal measui'es. The two Burlington species 

 are among the rarest Crinoids of that locality, and in the Coal 

 measures perfect calyces are rare, though fragmentary pieces have 

 been found in some localities in great abundance. 



The following species are known : 



1869. Erisocrinus antiquus Meek and Worthen. Proc. Acad. Nat. Sci. Phil., p. 



71 ; Geol. Rep. 111., vol. v. p. 447, pi. 2, fig. 3. Lower Burlington limestone. 



Subcarb. Burlington, Iow:i. 

 1865. Erisocr. conoideus Meek and Worthen. Proc. Acad. Nat. Sci. Phil., p. 150 ; 



Geol. Rep. 111., vol. ii. p. 318. Upper Coal Measures. Springfield, 111. 

 1865. Erisocr. typus Meek and Worthen. Type of the genus. Am. Jour. Sci., 2d 



ser. vol. xxix p. 174; Geol. Rep. 111., vol. ii. p. 319 ; ibid. vol. v. pi. 24, 



fig. 6. Upper Coal Measures. Springfield, 111. 

 Sy?i. Philocrinus pelvis M. and W. Am. Jour. Sci., 1866, p. 350. 

 Si/n. Erisocrinus Nebrascensis M. and W. Am. Jour. Sci. 1865, p. 174. 

 1869. Erisocr. Whitei Meek and Worthen. Proc. Acad. Nat. Sci. Phil., p. 72; 



Geol. Rep. 111., vol. v. p. 448, pi. 2, fig. 2. Upper Burlington limestone. 



Burlington, Iowa. 



B. Subgenus STEMMATOCRINUS Trautschold. 



18G7. Crin. d. jungeren Bergkalkes b. Moskau, p. 28. 

 1879. Kalkbriiche von Mjatschkowa, p. 125. 



Calyx low cup-shaped, truncate below; symmetry equilateral ; 

 all the plates of the catyx regularly alternating. 



Underbasals represented by a flat disc, which is undivided, 

 regularly pentagonal, and extending considerably beyond the pe- 

 riphery of the column. Basals pentagonal, abruptly bending 

 upward, the lower portion included in the truncate surface, the 

 upper almost vertical. Radials pentangular, twice as wide as 

 high, articulating lines straight and extending the full width of 

 the plate. Brachials one by five, pentagonal, of similar form with 

 the radials; the upper margin obtusely angular, its sloping sides 

 excavated to receive the arms. 



First arm plate simple, comparatively large, lower face rounded. 



