358 PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 



certain of its characteristics may be due to immaturity. The anterior 

 upper teeth (- 1 - and *) are of compressed, subelliptical shape, flattened on 

 the inner side ; * and A are triangular, with rounded angles, and - is ob- 

 scurely so ; the two dental series are nearly parallel, with only a slight ante- 

 rior divergence. 



The skull is very similar to that of Nematherium in form, being broad 

 behind, contracting rapidly forward to the interorbital region, and with 

 elongate and very slender face. The occiput is low and the upper contour 

 of the skull is gently arched from before backward ; the preorbital portion 

 of the face is distinctly shorter than in any species of Nematherium in 

 which the skull is well known, and the predental part of the maxillary is 

 also shortened ; the palate is of nearly uniform width and but slightly 

 convex posteriorly, where it is not continued so far behind the last tooth 



as in the preceding genus. 



MEASUREMENTS. 



Upper dentition, length 039 Skull, length occiput to anterior nares . .150 



1, length (i. e., antero-posterior di- Cranium, length to rim of orbit 114 



ameter) 006 Face, length orbit to anterior nares . . . .036 



" width (i. f., transverse diameter) . . . .0045 Occiput, height 031 



- 2 , length 007 Cranium, width at glenoid cavity 052 



" width 005 Zygomatic arch, length 075 



i, length 0065 Rostrum, width at infraorbital foramina .024 



" width 0065 " " " anterior end 021 



A, length 008 Palate, length in median line 047 



" width 007 " width at J- 0135 



, length 006 " " " * oio 



" width 004 



EDENTATA INCERTyE SEDIS. 



In addition to the foregoing genera Ameghino has named a number of 

 others, some of which he has referred to the Monotremata. These genera 

 are very imperfectly known and, as I am not in a position to add anything 

 to what has already been published, merely the names and references are 

 here given. 



TREMATHERIUM Ameghino. 



Trematherium Amegh. ; fenum. Sistem. etc., 1887, p. 22. 

 Trematherium Amegh.; Rev. Argent, de Hist. Nat, T. I, 1891, p. 319. 

 Schismotherium Mercerat, in part; Rev. del Museo de La Plata, T. II, 

 1891, p. 5. 



