384 f'roccc(liii(/s of llic Ohio State .Icadcmy of Science. 



1805. Sciiiiinila snbqmuivata. Hall and Clarke, Pal. X. Y., Vol. VIII, 

 pt. II, pi. 47, figs. 7-0, 15, 16; pi. 84, figs. 30, 81. 

 Kaskaskia limestone: Chester, Illinois; Crittenden County, Ken- 

 tucky. 

 St. Louis limestone: Pella, Iowa; Spergen Hill, Indiana. 

 18.05. Atljyris subquadrata. Whitfield, Geol. Surv. Ohio, Vol. VII, p. 

 47-_', ])1. in, ligs. 1-3. 

 Maxville limestone : Xewtonville and Maxville, Ohio. 

 1807. Atliyris siibqiiadrata. Weller, Trans. X^. Y. Acad. Sci., Vol. XVI, 

 p. 258, pi. 10, fig. Ifi. 

 Batesville sandstone : Batesville, Arkansas. 

 1903. Scniiniihi siihiiiiadrata. Girty, U. S. Geol. Surv., Prof. Paper 16, 

 p. 20(1, pi. 1, fig. 5. 

 Leadville limestone: Leadville district. Colorado. 

 Millsap limestone: Castle Rock quadrangle, Colorado. 

 1900. ScDiinula subquadrafa. Grabau and Shimer, X. A. Index Foss., 

 Vol. 1, p. 354. 

 Kaskaskia: Ohio, Kentucky, Illinois, Utah. 



Description. — Shell of medium size or smaller. sub(|ua(lrate 

 in outline, wider than long in most specimens ; the widest portion 

 being anterior of the middle. The bunching of the concentric 



a b c 



Fig. 13. — Seiiiiniila subquadrafa. 



a and b. — Dorsal and anterior views of the same specimen, 

 c. — Dorsal view of another individual, (.\fter Whitfield.) 



lines of growth at the anterior end often gives a thickened ap- 

 pearance to the shell. 



I'edicle vah'e ventricose at the posterior end, with extended 

 and inciH'ved beak, the extremity of which is trimcated thus 

 forming a round foramen. ^Mesial sinus increasing in depth and 

 breadth toward the anterior end. and culminating in a lingual 

 extension, limited on either side l)v a lateral fold. 



