170 R. 8. Lull — Fauna of the Dallas Sand Pits, 



the auditory bnlla is more inflated and lias a much greater 

 lateral area (see fig. 4). This greater development of 

 the bullae gives a longer contact with the basi-occipital 

 bone and separates the anterior and posterior foramen 

 lacerum much more remotely than in either existing 

 genus. The basi-occipital bears a distinct antero-poste- 

 rior groove which is lacking in the dromedary but present 

 in Auchenia. The postgienoid process is lighter in the 

 fossil. 



On the other hand, the occiput of the Dallas specimen 

 conforms rather closely with Hay's description' of the 

 type of Camelops liner fanensis (Cragin). In it he 

 speaks of the lambdoidal (nuchal) crest being thin and 

 sharp, a point of agreement. He also says that the 

 occipital surface in G. Imerfanensis bears ^^a median 

 descending ridge, rough and rounded, separating two 

 deep excavations, on each side of which is another deep 

 excavation at the bottom of which is placed the lateral 

 foramen." In the Dallas specimen the median ridge is of 

 less vertical extent, so that the excavations on either side 

 are confluent below, while in C. liuerfanensis they are 

 entirely separate. Hay speaks of the paroccipital pro- 

 cess being hooked at its extremity; this is not at all 

 marked in the Dallas specimen. 



Palate and dentition. — The chief tooth distinctions 

 between the Dallas Camelops and the dromedary lie, first, 

 in the total absence in the former of P^, the great size of 

 P, and the details of the cheek teeth, in which the meso- 

 style is less pronounced and is reflected forward. The 

 last molar bears a strongly developed posterior pillar 

 (metastyle) which is absent in the camel and but slightly 

 developed in Auchenia. There is no trace of an internal 

 basal pillar on the superior molar teeth. The dental 

 formula is in agreement with Auchenia as in Camelops, 

 while the teeth also agree quite closely with those of C. 

 huer fanensis even to dimensions (with due allowance for 

 wear), as the table of measurements shows. 



The posterior palatine foramina lie opposite ]\P as in 

 C. huerfanensis, although that on the left side is smaller 

 and is accompanied by a second, some distance behind the 

 first. In both Camelus and Auchenia the foramina lie 

 opposite the fourth premolars, those of the latter being 



^ O. p. Hay, Proc. U. S. Nat. Mus., 46, 270, 1913. ' 



