LEONTINIDAE 109 
Ancylocoelus is a valid genus, differentiated by its dental 
3043 
formula +23, 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 | 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. 1, p. 30. 
s*i+; type species L. gaudryt. Of all 
the animals in the Deseado, this is the most abundant. 
The formula is 
