LEONTINIDAE 109 



Ancylocoelus is a valid genus, differentiated by its dental 

 formula f^fy, the loss of the upper canine and the lower 

 canine and first premolar distinguishing it from either Leon- 

 tinia or Colpodon. 



Rodiotherium is based on a mandibular symphysis which 

 would indicate an animal with the same formula as the 

 foregoing genus, differing only in that lower incisor 3 is 

 large. This, to my mind, does not make a generic char- 

 acter, and at most the species, R. armatum, can only be 

 considered an independent species belonging to the genus 

 Ancylocoelus. 



Loxocoelus is a very questionable genus, based simply 

 on an upper molar, which "is similar to that of Homolo- 

 dontotherium, but more squared." I feel that in regard to 

 this genus it should stand as unknown until more material 

 is found. 



In our collection, over twenty skulls and jaws belonging 

 to this family turned up, but all clearly belong to two types, 

 the typical Leontinia gaudryi, and some others in which 

 the caniniform teeth are not so well developed, which are 

 either L. oxyrhynca or, as I believe, the females of L. gau- 

 dryi. It is this uniformity of the material which leads me 

 to doubt the validity of the considerable number of genera 

 which Ameghino has established, for I found on sectioning 

 the teeth that between the little worn crown and the much 

 worn one there was a marked difference in the appearance 

 of the infoldings and in the development of the pits. 



Leontinia Ameghino 



Leontinia Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 647. 

 Leontinia Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 469. 

 Scaphops Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 475. 

 Steniogenium Amegh., 1895, Inst. Geog. Argen., t. 15, p. 654. 

 Steniogenium Amegh., 1897, Inst. Geog. Argen., t. 18, p. 475. 

 Colpodon Gaudry, in part, 1906, Anal. Palaeontologie, t. I, p. 30. 



The formula is 3 3 ] \\ ; type species L. gaudryi. Of all 

 the animals in the Deseado, this is the most abundant. 



