114 THE DESEADO FORMATION OF PATAGONIA 



Ameghino has made six species of this genus, L. gaudryi, 

 L. fissicola, L. lapidosa, L. oxyrhynca, L. stenognatha, and 

 L. garzoni. All of the first five are described as of the same 

 size as L. gaudryi. L. garzoni is a smaller, about 60 per 

 cent, of the size of the others. Of the first five listed, the 

 first three have the large incisor and I consider them all 

 L. gaudryi. L. oxyrhynca and L. stenognatha are described 

 as having small canines and I believe that this is a sexual 

 difference only, so have considered these two species as 

 also belonging to L. gaudryi, but females. I have made a 

 careful comparison of L. gaudryi and L. oxyrhynca and find 

 them identical in all the features except in the region of the 

 canines where the latter is weaker, and can see no more 

 than sexual differences. Usually with this weakness of 

 the canine goes a smaller or lighter build of the lower jaw 

 which is what would be expected. The points by which 

 the various species were differentiated were, beside the size 

 of the canine, the presence or absence of pit 3, and the vari- 

 ation in the foldings on the outer sides of the lower molars, 

 which I find on sectioning a tooth appear deeper or shal- 

 lower according to whether the tooth was more or less 

 worn. 



Leontinia gaudryi Ameghino 



L. gaudryi Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 648. 



L. gaudryi Amegh., 1897, Bol. Gcog. Argen., t. 18, p. 472. 



Scaphops grypus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 629. 



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



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



Sk'iiiogcnium sclerops Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 475. 



Leontinia fissicola Amegh., 1897, Bol. Inst. Gcog. Argen., t. 18, p. 474. 



L. (Senodon) lapidosa Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 649. 



Females 



L. oxyrhynca Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 472. 



L. stenognatha Amegh., 1897, Bol. Inst. Geog. Argen., t. 15, p. 474. 



Colpodon gaudryi Gaudry, 1906, Anal. Palaeontologie, t. 1, p. 30. 



This species is represented in the Amherst Collection by 

 live more or less complete skulls, and over twenty jaws, 



