Review of Geinitz on the rocks and fossils of Nebraska. 181 
by Prof. King, a Cardiomorpha. It also differs from the Nebraska 
shell in having the internal ridge bounding the anterior muscul 
scar (as shown in the figures and mentioned in the description) 
ranging obliquely backward and downward at an angle of 45° 
to the axis of the valves, instead of nearly at right angles to the 
same, as shown in the figure of the Nebraska species. 
_ Ihave now before me an internal cast, and a specimen show- 
ing the exterior, of what are strongly suspected to be two very 
distinct types, that came from Germany with the name Clidopho- 
rus Pallasi attach The one showing the exterior agrees quite 
well with some of Prof. King’s figures of his Cardiomorpha modio- 
, ormis, which Prof. Geinitz cites as a synonym of the Russian 
species Pallasi; but the other specimen, that is, the internal cast, 
shows that it, at least, is a true Pleurophorus, as it has a hinge 
With teeth like the Nebraska shell; while one of Prof. King’s 
ugures of a cast and his description show that his modioliformis 
_ 18 edentulous, like the species Pallasi. 
From these facts, it seems highly probable that two types are, 
at any rate sometimes, confounded in Germany, under the name 
€. Pallasi ;* that is, one edentulous, agreeing perhaps specifi- 
cally with Prof. King’s moedioliformis, and another with a toothed 
Inge, or in other words a ‘true Pleurophorus. If the Nebraska 
ell belongs to any European species, it is far more probable 
that it is identical with Pleurophorus costatus, with casts of which, 
How before me from Europe, Prof. Geinitz’s figure closely agrees. 
4 _, Clidophorus (Pleurophorus) occidentalis M. & H. Geinitz, ib., tab. 
i, fig. 6. The shell figured under this name is certainly not the 
one is proportionally so slender and elongated as the not 
the jan shell. Nor have any of tats the posterior hing! 
teeth prolonged nearly so far backward. ye Ee 
_ Clidophorus side tce Geinitz, ib. fig. 7. This is a good spe- 
“les of genus ? tea 
. 
“he 5 Prof, Geinitz formerly confounded Pleurophorus costatus with 
the edentalou ce daten ‘Mytilus Pallasi. ie ae 
