128 



THE DESEADO FORMATION OF PATAGONIA 



genus is, that the crowns are expanded much wider than 

 the roots. While there is not yet enough direct evidence 

 to prove it, I feel that this and the next genus will prove 

 to be deciduous teeth, of either Proadinotherium or some 

 related genus. Two species of this genus have been de- 

 scribed, both from the upper Deseado. 

 I. phorcus Amegh., loc. cit. above. 



This species is characterized by its size, the last upper 

 molar (so called) measuring 16 mm. long by 14 mm. wide. 

 I. deflexus Amegh., 1904, Anal. Mus. Nac. B. A., ser. 3, 

 t. 3, p. 183. 



This species is based on a worn tooth designated as molar 

 1 (probably d. pm. 3) 14 mm. long by 19 mm. wide. 



Fig. 84. I. phorcus. 

 ' 'Upper molar 3 ' ' — natural 

 size, after Ameghino. 



Fig. 85. I. deflexus, 

 " Upper molar 1 " — natural 

 size, after Ameghino. 



Fig. 86. N. insulatus, 

 "Upper molar 1"— natural 

 size, after Ameghino. 



Nesohippus Ameghino 



Nesohippus Amegh., 1904, Anal. Soc. Cienc. Argen., t. 56, p. 34 of reprint. 

 Nesohippus Amegh., 1904, Anal. Mus. Nac. B. A., ser. 3, t. 3, p. 218. 



This genus is described as very like the foregoing, but 

 differs in having a strong perpendicular style on the ante- 

 rior external face of the upper molars. As in the preced- 

 ing genus, the crown is considerably expanded above the 

 roots. I feel that this genus will also prove to be the milk 

 teeth of some one of the genera of this family. One species 

 is described, based on a single tooth. 

 N. insulatus Amegh., 1904, loc. cit. under the genus. 



The species is just as described under the genus, the last 

 upper molar measuring 24 mm. long by 16 mm. wide; given 

 as from the upper Deseado. 



