I'HANOPHILUS 75 



seen by fig. 42, is narrow and high. A single 

 tooth measures 52 mm. from front to back, 

 and 3! mm. in width. 



Specimen 3142 gen. and sp. ? 

 This specimen is the mandible with the vi^'o^md!^?- 

 milk dentition. The molars present suggest 

 Prosotherium triangulidcns, but inc. 3 and the canine are 

 present, and the first two incisors are not enlarged, so it 

 would seem to represent a genus which I have not been 

 able to identify. Molar 1 is bilobed and similar to that of 

 Prosotherium. The deciduous premolars arc all present, all 



Fig. 44. Milk dentition, genus and species? — natural size. 



rooted, and all remarkable for their great antero-posterior 

 elongation. Roots of the incisors and canine are present, 

 that of the canine being the largest, and those of the incisors 

 being about equal in size. This would suggest such a 

 form as Protypothcrium, were this genus represented in 

 the Deseado beds. 



Interatheriidae 



The family is characterized by the incisors not being 

 enlarged, by upper and lower premolars and molars being 

 inflexed on both the inner and out sides, and by the inflated 

 mastoid bulla being filled with cancellous tissue. The 

 only genus referable to this family, from the Deseado 

 beds, is Archaeophylus. 



Archaeophylus Ameghino 



Archaeophylus Amegh., 1S97, Bol. Inst. Ceog. Argen., t. 18, p. 423. 



The genus is based on a skull which preserved most of 

 the upper dentition except the incisors, and which shows 

 the characteristics of the family in their inception. 



