256 TAL^^ONTOLOGT. 



satch limestone, at Dry Canon, Oquirrli Mountains, Logan and Ogden 

 Canons, Wabsatcli Range, Utah, and from a band of chert beneath the upper 

 black slates of the White Pine District. Collected by J. E. Clayton, S. F. 

 Emmons, and Arnold Hague. 



Genus ATHYRIS McCoy. 

 Atiiyris Claytoni n. sp. 



Plate IV, figs. 15-17. 



Shell of moderate size, oval or very slightly ovate in general outline 

 when viewed from the dorsal side, the entire length being one-sixth greater 

 than tha greatest width, and the rostral half of the shell being slightly more 

 attenuated than the forward part. Valves moderately and nearly equally 

 convex. Dorsal valve nearly circular in outline, convex, most ventricose in 

 the upper pai't, and somewhat angular along the middle throughout, but not 

 forming any distinct mesial elevation; beak small, incurved, and rather 

 pointed, the apex passing within the fissure of the opposite valve. Ventral 

 valve much longer than the dorsal, the rostral half very ventricose, but 

 becoming somewhat flattened on the antcro-median portion, without forming 

 a distinct sinus; beak large and tumid, abruptly curved upward, and 

 rather strongly truncated at the apex on a line with the plane of the valves; 

 cardinal margins strongly inflected or enrolled, almost ])resenting the appear- 

 ance of a cardinal area, but without any defined limits; fissure large, 

 broadly triangular, and partly filled by the dorsal beak. Surface of the 

 valves smooth, except a few strong concentric lines marking stages of 

 growth. 



The species is peculiar in shape, the cardinal portion presenting so 

 much the appearance of a species of Spirifer of the type of S. Maia Bill., 

 as figured in Pal. N. Y., vol. 4, pi. G?>, fig. 8, as to be readily mistaken for 

 one of that group; but the entire absence of a defined cardinal area, 

 together with the perforated beak, readily distinguishes it on a closer 

 inspection. The absence of any defined mesial fold and sinus is also a 

 good specific character. 



Formation and localitij. — In limestones of the Lower Carboniferous 

 (Waverly?) age, Little Cottonwood, 800 feet east of Reed and Benson's 



