354 PATAGONIAN EXPEDITIONS I PALEONTOLOGY. 



versely and set obliquely to the line of the jaw ; T has an unusually long 

 posterior lobe. 



The skull, so far as it is preserved, differs little from that of other 

 members of the family ; its upper contour is regularly arched from the 

 occiput to the end of the muzzle, and the preorbital region is quite short ; 

 the facet for the jugal on the maxillary is an unusually large and deep, 

 triangular depression. 



The measurements in the subjoined table are from the types in the 



Ameghino collection. 



MEASUREMENTS. 



Upper dentition, length 056 - 6 -, width 007 



1, length (i. e., antero-posterior diam- Skull, length 210 



eter) oio Lower dentition, length 056 



" width (/. e., transverse diameter) . . . .007 T , length 0065 



1, length oio " width 006 



" width 008 if, length 006 



i, length 0105 " width 008 



" width 0095 5, length 006 . 



A, length oio " width 0095 



" width 0085 T , length 020 



*-, length 0085 " width on 



NEMATHERIUM PROFUNDATUM (Ameghino). 



(Plate LXII, Figs. 2-2" ; Plate LXIII, Fig. 2.) 



Ammotherium profundatum Amegh. ; Rev. Argent, de Hist. Nat, T. I, 



1891, p. 325. 



Ammotherium aculeatum Amegh. ; fenum. Synopt. des Mamm. Foss. de 

 Patagonie, 1894, p. 168. 



The type of Ammotherium profundatiim is the nearly complete man- 

 dible of a rather old individual, with all the teeth in place, while that of 

 A. aculeatum is a finely preserved skull, with lower jaw, but lacking the 

 ascending ramus. There are, it is true, many differences between the two 

 specimens, but, in view of the great variability which characterizes this 

 whole group, it seems hardly probable that they represent two distinct 

 species. On the other hand, the palate with teeth which Ameghino subse- 

 quently referred to A. profundatum ('94, 168) (Plate LXII, fig. 5) may 

 well pertain to a different species. 



In size, this is one of the largest of the Santa Cruz Mylodontidcz, though 

 somewhat smaller than the preceding species. In the type of A. aculeatum 



