1 78 THE DESEADO FORMATION OF PATAGONIA 



and slow-growing animal. Most all of the material found 

 by any of the collectors falls clearly into this species. 

 Our specimens all came from the Chico del Chubut, west 

 of Puerto Visser, which point is about 250 miles north of 

 the locality where Gaudry's material was found. 



The general features of the skull have been given under 

 the generic description. The difference between this 

 and the preceding species lies in the absence of pm. i, 

 and the somewhat larger size. Both of our major speci- 

 mens are mutilated in places; and as the better skull was 

 found with only the zygoma tic arch exposed, we conclude 

 that the parts missing were lost before burial. On the 

 lower jaw the edges of some of the teeth were cracked off, 

 and both the ascending rami are lacking, both things having 

 happened before burial, this specimen being found well 

 in the bank and never exposed to weathering. It appears 

 as if the carcasses of the animals lay some time before 

 being buried by the sediments. The scattered condition 

 of all the finds indicates the same thing. The head of 

 our femur is still marked by the teeth which cleaned the 

 meat from the bone. The frequency of isolated tushes 

 indicates that many jaws originally containing them have 

 been either chewed to pieces or weathered away before 

 burial. I do not think all the tushes found originally 

 belonged to the lower jaw (Gaudry reports 18 tushes, all 

 lower); for the upper and lower tushes when isolated are 

 so much alike that it is difficult to distinguish them. 



The size of the skull is indicated by the following measure- 



ments: SPECIMEN No. 3207 



Length from inc. I to occipital condyles 720 mm. 



Length from front of premax. to nasal opening 225 mm. 



Length of boss on premaxilla 77 mm. 



Length of nasal opening at top 80 mm. 



Width of nasal opening at top 88 mm. 



Length from premax. to lambcloidal crest 540 mm. 



Width across zygomatic arches 35 mm - 



Width across frontal bones 90 mm. 



Transverse diameter of the snout 115 mm - 



