Appendix to Part II. 627 



but ivell defined, as is also the mesial ridge of the ventral. Area 

 not visible in specimens examined. 



Breadth, 1| ; length nearly the same ; thickness, 1^ of an 

 inch. 



Very near Spirifer linguifera of Phillips (a carboniferous lime- 

 stone fossil), but probably distinct. 



Bio Claro, Valley of Coquimbo, Chile. 



Tekebkatitla inca. — PL V. figs* 19, 20. 



Shell orbicular, depressed, surface obsoletely striated concentrically ; 

 the furrows of growth becoming more strongly marked towards 

 the margin. Dorsal valve most convex. Frontal margin ob- 

 soletely bisinuated, and in young specimens slightly truncate. 

 Beak of dorsal valve very prominent, and incurved, obtusely 

 angled at the sides, terminating in a {small ?) perforation. Area 

 very small but distinct. 



Length of dorsal valve, 1— ; breadth, l—of an msh; thick- 

 ness, 1 inch. 



Iquique, Southern Peru. 



