i.o6 University of Texas Bulletin 



larger, the first lateral lobe is broader than the branches of the siphonal, 

 the sides of the saddles still show teeth in places where they are entirely 

 smooth in our species. Some of these dififerencs may disappear in 

 larger specimens, but others, for example, the relative width of the 

 branches of the siphonal lobe of the first lateral, are probably per- 

 manent. The Russian species may consequently belong to Prothalas- 

 soceras, but it is certainly specifically different from ours. 



Age: 



Conglomerate at the base of the Hess formation, Permo-Carboni- 

 ferous. 



Number of specimens examined: 



One. Together with Mr. C. L. Baker, I have searched for a long 

 time at the locality without being able to find any other Cephalopod, 

 although other fossils were present. 



Locality: 



About 2j4 miles N 20° E from the old oil derrick on Wedin's ranch 

 at the foot of the first range of hills. Glass Mountains. 



