198 Cincinnati Society of Natural History. 
The only known species resembles Xestoleberis, but the thick 
valves forbid placing it with that genus. Aythocypris, and other 
genera of that type, also have thin valves, and are never so ventri- 
cose. It might perhaps have gone with Barychilina were it not for 
the fact that it has the left valve the largest instead of the right. 
PACHYDOMELLA TUMIDA, D0. sp. 
I HIS VSI LS STIR I Oi Uy (0 
Size: Length, 1.13 mm.; height, 0.75 mm.; thickness, o.8 mm.; 
right valve of same: length, 1.05 mm., height, 0.62 mm.; thick- 
ness, 0.48 mm. 
Carapace very thick, irregularly ovate, the ventral edge straight- 
ened, ends subequal, the anterior a little the narrowest. Right 
valve smaller than the left, most convex in the posterior half. 
Left valve overlapping the right, its edges thickened, especially at 
the dorsal side; point of greatest convexity very nearly central. 
Umbilical pit obscurely impressed, centrally situated. Surface 
irregularly wavy, sub-nodose. 
The ventricose carapace, thick valves, and rough surface readily 
distinguish this species. 
Position and locality: Devonian Bryozoa bed, Falls of the Ohio. 
BARYCHILINA, nN. gen. 
Carapace small, subrhomboidal or ovate; valves thick, unequal, 
the right the largest, overlapping the left except in the posterior 
half of the more or less convex dorsal side; the edges of the 
valves in this portion of the back are smooth, and resemble a pair 
of thick lips; (see pl. 13, fig 1¢) edges of both valves thick and 
smooth all around, that of the right valve much the heaviest. A 
sharply-defined narrow or rounded umbilical pit. Surface striate. 
Type, Larychilina puncto-striata, n. sp. 
In this remarkable genus we have a superficial ornamentation 
strikingly similar to that of the Devonian species of Lntomis, 
coupled with a restricted umbilical pit (instead of a long furrow) . 
and a thickness of the valves, especially of their edges, that is 
quite foreign to that genus. The inequality of the valves also is 
unknown in Extomis. The two last characters bring the peculiar 
genus Kyamodes, Jones, to mind, but the lobation of the dorsal 
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