392 rroci'cdiiifis of ihc Ohio Sfnir .Icudrinx (// Science. 



gin, often forming' undulations of the surface |\\ liittield, i8(;5|.'* 



Length 70 mm. 



This species is readily distinguished l)y its triangular out- 

 line and radiating plications. 



Iloricoii and locality. — Maxville limestone. 

 Upper zone : Thompson Residence, White Cottage. 

 Shale-nodular zone : Kroft Bridge, White Cottage. 



ALLORISMA ANDRE WSI-Whitf kid. 



1882. Allorisiiia Andrewsi. Whithekl, Aim. N. Y. Acad. Sci., Vol. 11^ 

 p. -J-i^. 

 MaxN'ille limestone: Newtonvillc, Ohio. 

 1888. AUoiisnia Andreivsi. Herrick, Bull. Denison Univ., Vol. IV,. 

 pi. 11, fig. 1-2. 

 Chester limestone: Ohio. 

 1891. Ailonsina Andrezvsi. Whitfield, Ann. N. Y. Acad. Sci., Vol. V, 

 p. 588, pi. 14, fig. (i. 

 Maxville limestone: Newtonville, Ohio. 

 lK}f). Ailorisiiia Aiidrczvsi^ WhitfR-ld, Geol. Surv. Ohio, Vol. VII, p.. 

 478, pi. 10, fig. Ci. 

 Ma.xville limestone: Newtonville, Ohio. 



Description. — Shell of medium size or larger, transverse 

 outline ohovate, longitudinal outline suhrectangular. \'alves 

 ventricose, most so along a line extending diagonally from the 



Fig. 18. — Allorisiiia andrcii'si. A view of the right valve. (After Whit- 

 field.) 



beak to the posterio-ventral angle, and with a slightly concave 

 line parallel with and dorsal to the former. Ventral margirr 

 convexly curved and parallel with the dorsal margin. Posterior 

 margin broadly rounded. Anterior margin more abruptly 



