14 Brachiopoda of the Cincinnati Group. 



Pholidops cincinncdienm — (Hall, 1872). 



Shell small, ovate in outline. Larger valve about one fifth longer 

 than wide, with height one third to one fourth the breadth. Apex 

 obtuse, near half way between the middle and the larger end. An- 

 terior end narrowly rounded, posterior end somewhat more broadly 

 rounded, or almost subtruncate. Surface ornamented by six or seven 

 subimbricating marks of growth. Smaller valve unkno^yn. 



Length, 0.14 inch; breadth, 0.12 inch; height of larger valve, 0.04 

 inch. 



This species is quite rare, and yet it has been found, at Cincinnati, at 

 nearly all elevations, from low water-mark to the top of the hills, back 

 of the city. Its range is, therefore, not limited to less than half the 

 thickness of the Cincinnati Group, and is probably more extended. 



Family Discinidce. 



Animal attached by the means of a muscular peduncle, jDassing 

 through the ventral or lower valve, a sht in the hinder portion, or a circu- 

 lar foramen excavated in the substance of the same valve. Arms fleshy ; 

 valves unarticulated. 



This family includes with other genera the genus Trematis. 



Genus Trematis — (Sharpe, 1847). 



Animal unknown ; shell somewhat depressed, suborbicular or trans- 

 versely oval; both valves slightly and unequally convex, giving a len- 

 ticular form to the shell; umbo of the upper or imperforated valve 

 submarginal, slightly projecting. Lower or ventral valve with a sub- 

 central umbo, behind which a narrow, oblong, oval slit reaches to near 

 the posterior margin, and afforded passage to the pedicle fibers of 

 attachment. 



Internal disposition unknown ; a wide cardinal margin is visible in 

 the imperforated valve. 



Trematis terminalis (f) — (Conrad, 1847). 



Shell very obtusely subovate or orbicular; ventral valve nearly 

 flat, with a narrow, deeply depressed pedicle opening about one fourth 

 the length of the shell and extending to the' margin of the shell 



