564 THE JOCLRINATLROLAGHOLO GV: 
species P. alleghantensis, destructor and securiger shall prove to be 
one, then it appears reasonable that they shall receive the name 
P. ohioensis. As regards the relationship of P. alleghaniensis to P. 
destructor it must be noted that the teeth called by the former 
name are considerably smaller, the breadth of the crown of the 
one figured in the “Extinct Vertebrate Fauna” having a breadth 
of crown of only 20™”, while the crown of the specimen fig- 
ured by Messrs. Newberry and Worthen has a width of 42™. 
For the present I am inclined to regard P. alleghamensis and 
P. securiger as distinct species and to refer P. destructor to P. 
ohioensis. 
Figure 1 represents the posterior face of the tooth of P. secu- 
viger, While Fig. 2 is intended to present a section through the 
tooth. However, the anterior face of the root has not yet been 
freed from the matrix. Two teeth of this form have been 
brought to me by Mr. Harry Derr, of Chicago, who collected 
them in the Carboniferous limestone at La Salle, Ill. One of the 
teeth was considerably broken and parts were missing. 
To Professor C. W. Rolfe, of the University of Illinois, I am 
indebted for information regarding P. destructor. 
Oy, IPs Ialave, 11,10). 
FIELD COLUMBIAN MUSEUM, 
Chicago, July 12, 1895. 
