82 PATAGONIAN EXPEDITIONS: PALEONTOLOGY. 



Measurements. 



T^, width OI2 Mi width 0185 



P-^, length 012 M^, length 014 



" width 016 " width 019 



pi-, length 014 M^, length 0125 



" width 017s " width 019 



Upper molar series, length . -. .039 Cranium, width at constriction . .036 



Mi length 0125 Rostrum, width 029 



Locality. — Not given. 



Tetramerorhinus lucarius Ameghino. 

 (Plate VII, Figs. 10, 11.) 



Tetramerorhinus htcarms Avatgh..; Enum. Synopt., etc., 1894, p. 40. 



The separation of this species from Proterotherium is of even more 

 doubtful propriety than in the case of T. fortis, from which it differs in 

 its decidedly smaller size. The teeth are very similar in size and struc- 

 ture to those of Proterot/ieriicm cavum, to which, it seems very probable, 

 this species should be referred. Such differences in the tooth-pattern as 

 may be noted are no greater than may well be regarded as mere individ- 

 ual variations. Thus, p- has a smaller and less prominent inner tubercle, 

 while in p- and - the postero-internal cusp (tetartocone) is somewhat larger. 



Though unwilling to make any positive statement from the exami- 

 nation of a cast, I cannot but think that the division of the nasal bones, 

 which is asymmetrical and irregular, is a result of the vertical down-crush- 

 ing which the skull has evidently undergone. The somewhat unusual 

 width of the rostrum is probably likewise a result of the same cause. 

 Should, however, the division prove not to be due to crushing, it would 

 go far to confirm Ameghino's interpretation, as it is very unlikely that 

 individuals of different species should show the same abnormality. 



Measurements. 



Upper premolar-molar series, length. .0675 P-t, length ..... .0105 



" premolar series, length. .. .036 " width . . . . . .013 



pi, length (/. f., ant.-post. diam.) . .008 Upper molar series, length . . .032 



" width (z. f., greatest trans, diam.) .005 Mi, length . . . . . .011 



P-^, length ..... .009 " width . . . . . .0155 



" width . ... .008 M.^, length 012 



P-2-, length 010 " width 016 



" width ..... .012 M-2- length ..... .010 



Locality. — Not given. 



