SAGENOCRINIDAE 245 



The Species of Forbesiocrinus 



I. Solid anal and iBr plates confined to lower part of areas. 

 iBr areas narrow. iBr few. 



Surface smooth. Specimens small F. communis. 



iBr areas wide. iBr well-developed. Surface pustulose. 



Specimens large F. nobilis. 



II. Anal and iBr areas filled with solid plates connecting with tegmen. 

 Calyx plates elevated. 



Rays prominently elevated. 

 Calyx obtusely pentagonal. 

 R and lower Br long. 

 Calyx plates nodose. 



Specimens large. IBr 2 F. agassizi. 



Specimens small. IBr 3 F. burlingtonensis. 



Rays but slightly convex. 



Calyx obtusely decagonal, subglobose. 

 R and lower Br short and wide. 

 Calyx plates slightly rounded. 

 Arms long, flat, abutting. 



Calyx short F. wortheni. 



Arms rounded, separated. 



Calyx higher F. inultibrachiatus. 



Calyx plates tumid. 



Arms flat, delicate, abutting. 



Calyx higher F. zvashingtonensis. 



Calyx circular, conical. 



Arms rounded, well separated F. pyriformis. 



Calyx plates flush with general curvature. 



Calyx globose, circular F. greenei. 



Calyx lobed, pentagonal. 



IIBr 3 prominently convex F. saffordi. 



Forbesiocrinus communis Hall 

 Plate XX, figs. 4-8 



Forbesiocrinus communis Hall, Prelim. Notice 17th Rep. N. Y. St. Cab. Nat. Hist., 1863, p. 6 (Final Rep., 

 1864, p. 55). — Hall and Whitfield, Geol. Surv. Ohio, Pal. II, 1875, p. 169, pi. 12, figs. 4, 5 (not fig. 3). 



Taxocrinus communis, Meek and Worthen, Proc. Acad. Nat. Sci. Philadelphia, 1865, p. 140. — Wachsmuth 

 and Springer, Revision Palaeocrinoidea, pt. 1, 1879, p. 48. 



A rather small species. Crown spreading to top of first JIBr, where height 

 to width is 1 to 1.5. Spread of calyx from base, 1 to 5.5; rays and- their divisions 

 deeply rounded, with wide spaces between them. Surface smooth ; sutures more 

 or less sinuous, not beveled or imbricated. Maximum crown to fourth bifurca- 

 tion, 32 mm. high by 22 mm. wide ; base, 4 mm. 



IBB low pentagons as seen beyond the column. BB not over half the size 

 of RR, except post. B which is larger than the others, angular above, supporting 

 2 (sometimes 3) rather small plates suturally united to adjacent Br; these are 

 followed at the right side by a series of small plates united to r. post, ray which 

 may extend as high as the second bifurcation. Primary iBr one large plate, 



