688 THE PALEONTOLOGY OF MINNESOTA. 
[Bythoeypris cylindrica. 
of the interior. This internal thickening recalls Cytherellina siliqua Jones, which 
this species also resembles in its external characters, but the casts of that species 
are marked with two sulci instead of one. Still, 1am not all satisfied that these two 
forms are not strictly congeneric. The sulcus in the casts of B. cylindrica being just 
behind the center, it corresponds with the posterior one of the two in the Cytherell- 
ina. As to the anterior one, would its absence be of any great consequence? While 
it does not seem to me now that it would be, it is deemed wisest to defer a decision 
on the point, since the verdict would necessarily involve many others of the paleozoic 
species now referred to Bythocypris. Of the latter, B. testacella Jones, from the 
Wenlock of England, differs chiefly in being more elongate and less broadly rounded 
posteriorly. 
In the Canadian publication above cited, I referred a valve from the Hudson 
River group of Manitoba, to this species. That the identification was incorrect, I 
am now fully convinced. The figure, which was probably drawn in a reversed 
position, shows a left valve, agreeing very closely with the Wenlock species B. 
concinna Jones. Perhaps it should be referred to that species, but it would be well 
to await the discovery of more conclusive evidence before such a course is finally 
decided upon. ; A 
It is scarcely necessary to show why B. cylindrica.is neither a Primitia nor a 
Leperditia, As to its identity with Hichwald’s Cypridina, later Leperditia minuta, 
which Prof. Jones refers to Primitia (loc. cit.) and I to the new genus Primitiella, is a 
question that it seems to me can be answered only in the negative. The minuta, as 
figured by Prof. Jones from Russian examples of the species, has dorsal angles with 
a long straight back, giving it on the whole a decided primitian aspect, which 
certainly is not the case with the true B. cylindrica. In the same paper Prof. Jones 
figures two Cincinnati specimens, presumably of the latter species, to show their 
similarity or identity with the Russian P. minuta. He represents them as having a 
straight hinge and obtuse dorsal angles, the valves being figured, according to my 
interpretation, in a reversed position. As to these features I can only say that I 
have never seen any specimen in which they were present; and this can scarcely be 
because of a lack of material, for, of all the Cincinnati Ostracoda, b. cylindrica is by 
far the most abundant. Prof. Jones’ figures being like Hall’s figure of the species, 
is it not possible that the drawing of the former was biased by an examination of 
the latter? 
Formation and locality.—Rare in the Galena shales near Cannon Falls, Minnesota. Very abundant 
in the lower beds of the Cincinnati group, at numerous points in the vicinity of Cincinnati, Ohio. Very 
large specimens, 2.0 mm. and more in length, occur in the upper beds of the same formation. These were 
referred to the species by Dr. 8. A. Miller, but are not taken into account here because they are probably 
distinct. 
