414 White and Cope—The Green River Group. 
whether the typical strata of either the Green River or Wahsatch 
Groups were ever continuous with these northern strata or not, 
we have in that upper one hundred feet of Sentinel Butte the 
chronological representatives of the Upper and Lower Green 
River and the Wahsatch Groups combined. Whatever the 
facts of the equivalency of the strata here discussed may be, 
I have no doubt that the small fish-bearing deposit in question 
was laid down in waters that immediately succeeded the close 
of the Laramie Group, and that it is not properly a part of the 
same although it rests with apparent conformity upon it 
e following is Professor Cope’s description of the fishes 
referred to in the foregoing remarks : 
On a new extinct genus and species of Percide from Dakota 
. Territory ; by E. D. Cops. 
The specimens of fishes submitted to me by Professor C. A. 
White represent four individuals and two species. These be- 
long apparently to the Centrarchine division of the Percide, 
and although the future discovery of the structure of the ven- 
tral fins may invalidate this conclusion I do not anticipate such 
a result. JI am also unable to determine whether there are teeth 
on the vomer or not. As regards generic affinity the species do 
not enter any of the genera now known from American or Hu- 
spinous rays originating posterior to the line of the anterior 
border of the spinous dorsal fin. i 
Plioplarchus, and give the following diagnosis. Family charac- 
ters, etc.: Mo 1 
uninterrupted. 
The species may be described as follows :— 
Plioplarchus Whitei Cope. 
General form elongate oval, the dorsal and ventral outlines 
of the body about ie ae convex, The length of the head 
enters that of the head and body to the extremity of the cauda 
