582 FL B. Meek—Fossils of the Illinois Geological Report. 
At any rate, whatever importance may be attached to the 
peculiarities of the hinge we have illustrated, so far as regards 
the relations of these shells to Schizodus, I have no doubt that 
the little shell from the Kansas Coal-measures, for which Mr. 
opinion that these shells belong to the Unionidae (Naiades). 
On the contrary, their entire combination of characters, no less 
than their constant association with marine types, seem to me 
to indicate different family relations. That is, they seem to be 
directly connected, through the typical Schizodus, and the vari- 
ous forms included in the genus Myophoria, with the Trigonude, 
as maintained by Prof. King. 
et, if farther comparisons should show that Mr. Conrad’s 
name must be retained in a subgeneric sense, under Schizodus, 
the name of our species, represented by fig. 14a, 8, ¢, will 
doubtless have to be written S. (Prisconaia) curtus, as it almost 
certainly has the same hinge-characters; and I even suspect 
Mr. Conrad’s type, P. ventricosa, may be specifically identical 
with it* .— 
It will be seen, by examining our figure 17e, that the sur- 
face of these shells, when perfectly preserved, and examined 
under a strong magnifier, in a favorable light, shows very ml- 
nute, exceedingly regular and peculiar sculpturing. I am not 
aware that any. such markings have ever been observed on the 
i 
the slightest abrasion. Indeed, so very minute is it, that it 
would generally escape observation, unless especially looked 
for. On calling Mr. Conrad’s attention to it, he wrote me that 
he found it to be beautifully defined on the type of his pro- 
posed genus Prisconaia. 
Solenomya (sp. undt.); pl. xxv, figs. la, d—I have long 
been familiar with this shell among our Coal-measure fossils of 
the West, but have never been quite able to come to a satisfac- 
conclusion in regard to its relations to a species figured 
and described by Prof. Cox, in the third volume of the Ken- 
*T cannot ith Mr. others, itute a new name 
Aszinopsis, or a, aa page Kings a ene nee because the 
name Schizodon had - previously used for genera of Fishes and Mammals. 
