162 PROCEEDINGS OF THE ACADEMY OP [1883. 



Bhineastes from our eocene beds, except perhaps the JR. arcuatus, 

 iu the possession of but one row of teeth. The surface is delicately 

 striate. The anterior edge is smooth and acute, and the posterior 

 edge has two rows of serrffi separated by the usual groove. 



COTTID^. 

 COTTUS L. 



I refer to this genus four species from the Idaho beds. They 

 maj^ belong to Uranidea^ but as I can only identify them as y&t 

 by the preopercula, I cannot determine this point. The parts in 

 question are not rare, showing that this type was well represented 

 in this region. 



The preopercular bones are furnished with three or four acute 

 spines of no great length. In this they differ from the living 

 American species of Uranidea, which have only one or two spines, 

 excepting the U. spilota, which has (fide Jordan) four spines, 

 three of which are inferior. The four species of the present col- 

 lection differ in their prominent features, as follows : — 

 a. Foramina on inner side of preoperculum. 

 Four spines ; angular spine directed backwards ; inferior ones 

 forwards ; smaller ; G. divaricatus. 



Angular spine directed backwards ; posterior inferior downwards ; 

 inner side with two faces separated by an angle ; larger ; 



G. pontifex. 



aa. Foramina on the posterior edge of preopercle. 



Angular spine directed backwards ; two strong similar inferior 



spines turned forwards ; larger ; G. cryptotremus. 



aaa. No foramina. 



Angular spine directed downwards ; inferior spines forwards ; the 



anterior inferior flattened ; large ; G. hypoceras. 



Cottus divaricatus sp. nov. 



Represented by two preopercula. These indicate the smallest 

 of the four species, and one about equal to the G. richardsoni^ 

 Ag. The preoperculum is flatter and thinner than in the other 

 species, and the foramina are all on the inner side of the branches. 

 These are : one large one above base of superior spine, one small 

 one between bases of superior and angular spines, one do. between 

 bases of angular and posterior inferior, and one at anterior base 

 of posterior inferior. The two inferior spines are smaller than 

 the others, and are incurved. The superior posterior is the largest 



