II i;i.i)i:i!i{i;;!(i Fouma tion in M.\i;vi.and 41 



of the genus that has been found in the state. The specimen being broken 

 otr just posterior to the beaks prevents determination but it probably is a 

 new species. 



Occurrence. — HELDKHUKna FomiAxiox, Kkysku j\[i:.Miii;i;. Keyser, 

 West Virginia. 



Collection. — U. S. National Museum. 



Family AMBONYCHIIDAE 



Genus AMPHICCEl.IA Hall 

 AMPHTCaiLIA ULRICTII n. sp. 



Plate LXXY, Figs. 8-10 



Description. — Broadly triangular subovatc in outline. Length and 

 height about equal, ^'alvcs equal, somewhat gibbous from the center to 

 the beaks, sloping abruptly to the anterior margin, while the decline from 

 the most gibbous portion of the shell to the posterior and ventral margins 

 is more gradual, giving to the shell a cuneiform profile. The cardinal line 

 arcuate. Cardinal slopes concave in the vicinity of the beak in the casts. 

 Anterior and posterior cardinal margins and ventral margin regularly 

 rounded. In the posterior portion of the shell at the point of greatest 

 length, the shell is extended making the form inequilateral. The umboncs 

 in the better preserved individuals are equal and opposite, broad and 

 gibbous, and are curved inward and forward over the hinge-line and placed 

 considerably anterior to the middle. Surface of both valves marked by 

 moderately strong radiating cost®. The costas are low, rounded, and 

 simple, six or seven occupying the space of 5 mm. in the umbonal region, 

 the costffi are indistinct toward the base in the individuals at hand, but 

 the general appearance indicates that they become wider toward the base. 

 Shell varying in size from small individuals to quite large ones for this 

 genus. 



This species most closely resembles Aniphicalia costata (Hall and 

 Whitfield) of the ISTiagara of Ohio. It differs, however, in being less 

 ventricose, the beaks are more nearly central, and the costa? are more 

 numerous. 



