Peterson : Osteology oi- Oxvdaciylus. 46*.) 



Oxydactylus brachyodontus sj). nov. 



The type (No. 664) (I'l. XI, Figs, i, 2 and 3) of the above 

 named species is represented by a fairly complete cranium with the 

 lower jaw in position and the atlas, anterior portion of the axis and 

 the succeeding five cervicals, the distal end of both humeri, both 

 ulnae and radii, the carpals, metacarpals and phalanges, the left femur, 

 the tibia, calcaneum, astragalus, cuboid and metatarsals. There is 

 another nearly complete skeleton (No. 562) which I have provi- 

 sionally referred to this species ; but unfortunately no part of the skull 

 or lower jaw is present. The two individuals do not differ greatly in 

 size. No. 562 being only a little larger than No. 664. The principal 

 differences between this species and O. longipes are as follows : 



The Cranium. — In comparison with that of O. longipes the cranium 

 is relatively large. The second and third incisors are present and 

 part of the alveolus for the first. The third incisor is smaller than 

 the canine. The first premolar which is somewhat reduced, is sub- 

 conical and has a single root. Premolars two, three and four are 

 similar to those of O. longipes. The molars are brachyodont, broad 

 and comparatively short antero-posteriorly. The outline of the skull 

 is similar to that of O. longipes. The fronto-nasal suture is perhaps 

 placed a little farther back than in the latter species. 



The Mandible. — The lower jaws present characters very like those 

 oi Pro f ornery X i^Goniphotheriuni) cameloides,"^^ agreeing especially in 

 the absence of a diastema between the incisors and canine. In O. 

 brachyodontus the incisors are more reduced than in Protoineryx camel- 

 oides, but have the same spatulate shape. In the type of O. brachy- 

 odontus the teeth are much worn (PI. XI, Fig. 4). The first pre- 

 molar is fixed by two strong roots, and, as in the upper jaw, the 

 crown is subconical with the greater diameter directed antero-pos- 

 teriorly. In Protoineryx catneloides this tooth has a greater antero- 

 posterior diameter and has quite distinct anterior and posterior basal 

 tubercles. In the type O. brachyodontus the second, third and fourth 

 premolars do not differ materially from those of O. longipes. The 

 true molars differ from those of O. longipes by being proportionally 

 broader and shorter. 



The Cervicals. — (PI. XII, Figs, i, 2, 3 and 4.) The cervicals 

 are comparatively short and heavy. The axis and the third cervical 



^^Btd. Am. Mils. A<7t. Hist., p. Ii8, 1898. 



