112 THE DESEADO FORMATION OF PATAGONIA 



on the sides of the skull, bounding the lower part of the 

 orbit, and having a short zygomatic process. The small 

 lachrymal is but little exposed on the exterior surface of 

 the skull, the lachrymal pit being well inside the orbit. 

 The zygomatic arches are broad and heavy, and composed 

 mostly of the wide jugal bones. The palate is highly arched 

 and relatively narrow, the crowns of the premolars and 

 molars projecting inward over it, thus narrowing it still 

 more. It extends back well beyond the last molar. The 

 large tympanic bullae are hollow, and the cavity in the 

 squamosum seems to be reduced in size, as compared with 

 Rhynchippidae or Nesodontidae. The occipital condyles are 

 set well apart and are sessile; and the paroccipital proc- 

 esses are long and slender. 



The atlas, axis and cervical 3 are associated with the 

 skulls. The atlas is short, heavy, and has the anterior 

 cotyles broad, deeply excavated and wide apart; while the 

 posterior cotyles are nearly flat, and high as well as wide. 

 The transverse processes are only moderately wide, but are 

 very heavy, especially along the posterior margin. The 

 centrum of the axis is flattened, the neural canal, wider 

 than high, and the neural spine of moderate height. The 

 anterior cotyles are broad and moderately convex, and the 

 odontoid process is a stout peg-like process, somewhat 

 higher than wide. Slender transverse processes project 

 sharply from the centrum, and have at their bases a large 

 canal for the vertebral artery. Cervical 3 is shorter than 

 the axis, has a less depressed centrum, a small neural spine, 

 and short wide transverse processes. 



Though I have skulls and jaws to represent some twenty- 

 five individuals, no limb material was found in direct asso- 

 ciation with any of them. However we did find a humerus, 

 radius and ulna on the same level and about fifteen feet 

 front one of the skulls, and as it corresponds in size, and as 

 humeri of this type are the most abundant skeletal bones 

 found (as is also the case with the skulls), I have considered 



