70 



PATAGONIAN EXPEDITIONS: PALEONTOLOGY. 



Proterotherium brownii sp. nov. 



(Plate IX, Figs. 2, 2a.) 



The type and only known representative of this species is a specimen 

 belonging to the American Museum of Natural History (No. 9568) and 

 containing the upper dentition almost complete and unworn. The species 

 closely approximates P. mtstrale in size and the grinding teeth most 

 resemble those of the latter. The second upper premolar has two small 

 and conical internal cusps, which are almost median in position, and a 

 large posterior heel, defined by the elevated cingulum. This pattern is 

 different from that of the corresponding tooth in any other species which 

 I have observed, and, if constant, is doubtless a valuable diagnostic char- 

 acter. In p- and - the tetartocone is well developed and in the upper molars 

 the posterior conule is almost exactly midway between the two internal 

 cusps. M- is remarkable for the extreme reduction of the postero-external 

 cusp, a reduction greater than in any other known example of the genus. 



Measurements. 



Upper dentition, length i^-m^ 

 I-^, antero-posterior diameter 



" transverse " 



Upper premolar-molar series, length 



" premolar series, length 

 pi, length {i. e., ant.-post. diam.) 

 ; " width (/. e., transverse diam.) 

 P2, length .... 



" width .... 

 Pl, length .... 



.106 



.007 

 .0075 

 .076 

 .042 

 ?.oo8 

 .007 

 .0105 

 .0115 

 .012 



P^, width CIS 



P-t, length 0125 



" width 016 



Upper molar series, length . . .0365 

 Ml, length 013 



" width 017 



M^, length 014 



" width 018 



M-3., length 010 



" width 018 



Locality. — The type was collected by Mr. Barnum Brown at Monte 

 Leon. 



This species is named in honor of Mr. Brown, who discovered and 

 collected it. 



Proterotherium brachygnathus Ameghino. 



(Plate X, Figs. 12, 13.) 



Proterothermm brachygnatJmm Amegh.; Enum. Synopt., etc., 1894, p. 38. 

 Licaphrimn proclivtini Amegh.; Ibid., p. 42. 



The type of this species is a fragment of the symphysial region of the 

 mandible, with only one tooth, pi of the left side, intact. The lower tusk 



