114 THE DESEADO FORMATION OF PATAGONIA 
Ameghino has made six species of this genus, L. gaudryz, 
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. Geog. 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. 
Steniogenium sclerops Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 475. 
Leontinia fissicola Amegh., 1897, Bol. Inst. Geog. 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 
five more or less complete skulls, and over twenty jaws, 
