158 Cincinnati Society of Natural History. 
Formation and locality: Cincinnati group. Not uncommon on the 
hills back of Cincinnati, O., and Covington, Ky. 
LEPTOTRYPA, N. gen. © 
Zoaria thin, incrusting foreign bodies, occasionally overgrowing 
the latter and becoming partially free. Cells polygonal, thin-walled, 
apparently of one kind only. Surface with monticules or without, 
usually, however, showing more or less distinct groups of large cells. 
Spiniform tubuli small, numerous, generally occupying only the angles 
of junction of the cells. Diaphragms wanting or but sparingly developed. 
Type, L. minima, n. sp. 
This genus includes a group of species that I have found it quite 
impossible to distribute among the genera of Monticuliporide already 
established. They can not be placed with Atactopera, the species of 
that genus being provided with spiniform tubuli which are always 
placed within the substance of the cell-walls, and project prominently 
into the cell-cavity, so as to give it a petaloid appearance. In Lepto- 
trypa they are always situated between the walls, and are only rarely 
developed excepting at the angles of the cells. They have but little 
affinity with the species of Spatiopara, the cell-structure in the two 
genera being quite different, 
Tangential sections of Leptotrypa somewhat resemble those of cer- 
tain species of Amplexopora, but they differ so widely in growth, and 
other respects, that I am forced to regard them as quite distinct. How 
nearly Leptotrypa is allied to Nebulipora, McCoy, 1 am unable to say. 
I have in vain tried to gain something like a satisfactory knowledge 
of the species upon which McCoy founded his genus. Specimens said 
to be Nebulipora papillata, prove, upon investigation, to belong to a 
species of Ceramopora. Even if an examination of McCoy’s types, 
which may no longer be possible, should show the above identification 
of his species to be erroneous, and my genus a synonym, I ought not 
to be blamed, for, after carefully considering the question, I have come 
to the conclusion, that to prupose a new genus for the reception of my 
species, will cause less confusion than to place them into a genus, the 
characters of which no one seems able to define with any degree of 
certainty. 
Beside the four species next described, I propose to include in the 
genus Leptotrypa, Chetetes discoideus, James (Nicholson), and two 
Niagara group species, which Hall has, erroneously I believe, placed 
in his genus Paleschara, under the names of P. offulu and P. maculata. 
