Il6 PATAGONIAN EXPEDITIONS: PALEONTOLOGY. 



different species. In T. garrettorum these processes are broad and con- 

 spicuous and widely separate the nasals, while in T. lallemanti [lydekkeri), 

 as figured by Ameghino [loc. cit.), they are very much reduced. 



The surface of the frontals is quite smooth and there is no indication of 

 the deep median depression, with pits and ridges for the insertion of the 

 muscles of the proboscis, which is so very conspicuous a feature in the 

 skull of Macrauchenia. 



The nasals are greatly reduced and very short, though much larger than 

 the vestigial remnants seen in the Pampean genus ; they are strongly 

 curved transversely and almost semicylindrical, with dorsal and lateral 

 faces. According to Ameghino's figure {loc. cit.), in T. lallemanti, the 

 nasal processes of the frontals are short and narrow and the nasals them- 

 selves are in contact for nearly their entire length. In T. garrettorimi, 

 on the contrary, the very large processes so separate the nasals, that they 

 do not touch each other at any point. The great shortening of the nasals 

 is an indication that some sort of a proboscis, or prehensile upper lip, 

 must have been present in the living animal, while the absence of any 

 special area for muscular attachments shows that the proboscis cannot 

 have attained any such development as it had in Macrauchenia. The 

 anterior narial opening is very long and narrow, differing much in shape 

 and position from that seen in the Pampean genus. As a whole, the 

 opening is much more anterior in position than in the latter and extends 

 forward between the maxillaries for their entire length and even slightly 

 invades the premaxillaries, and posteriorly, it terminates in front of the 

 orbits, which themselves occupy a more anterior position than in 

 Macrauchenia. 



The maxillaries are very elongate and immediately in front of the orbits, 

 where they articulate with the nasals, they have considerable dorso-ven- 

 tral height, but from the end of the nasal suture this height diminishes 

 rapidly and the anterior portion of the maxillaries is very low. Except 

 in the palatal region, the two maxillaries are nowhere in contact, being 

 separated for their entire length by the anterior nares. The infraor- 

 bital canal, which is rather small, opens above m-. The premaxillaries 

 are relatively elongate and very low dorso-ventrally, and are not distin- 

 guished into alveolar and ascending rami. They are broad, depressed 

 and flattened, slightly convex on the dorsal surface and overlapping the 

 maxillaries behind. For most of their length, the two bones are in contact. 



