670 



DR. n. UUOOM ON THE STRUCTUUE OF THK SKULL 



The type consists of most of the preorbital portion of a skull 

 with much of the left postorbital region and with an incisor 

 portion which probably belongs to the same skull, but the contact 

 has been lost. Besides these portions, which probably belong to 

 one skull, there is much of the postorbital portion of a second 

 skull, and much of a lower jaw which may belong to either of the 

 skidls — more probably to the first. 



There are four large incisors, of which the first is of Dino- 

 cephalian type, but the other three incisors may have had pointed 

 crowns. There is some little indication that this may have been 

 so. The canine is large and somewhat curiously bent. There 

 are five well-developed molars which occupy a space of about 

 54 mm. 



In the figure I give (text-fig. 8), some idea of the shape of the 

 skull will be obtained. The surface of the bone is flaked off, so 

 that the sutures given may differ a little from those that would 

 appear on the surface. 



Text-fioure 8. 



■-N 5?. ; 



Side view of skull of Dinartamus vanderbi/li, gen. et sp. iiov. 

 About y nut. size. 



The lower jaw which I believe to belong to this species and 

 probably to the same skull is quite remarkable. There are 

 apparently three incisors and what look like two lai-ge canines. 

 It is probable, however, that the first is the true canine, and 

 that the other is an enlarged first molar. Following the 

 enlarged first molar are foiu" fairly normal molars. If this 

 view be correct, the dental formula of Dinartamus Avill be 



.41 5 



It will be seen that Dinartamus difters considerably from the 

 typical Titanosuchids such as Scajxinodoii and Dinojjhoiieus, and 

 ought to be placed in a distinct family which may be called the 

 Dinartamidai. 



I do not intend in the present paper to enter into the dis- 

 cussion of the affinities of the Titanosuchids with the Tapino- 

 cephaloids, or the more interesting question of their affinities with 

 the other Therapsids. But in the meantime one may suggest 



