Peterson: Osteology ok OxvDAcrvLUs. 471 



pes. The carpal series presents no important difference from that of 

 O. /ofi}^!/>('s. The metacarpals are long, slender, and distally spread 

 more distinctly than in O. /ont^ipes. As in the latter species the carina 

 is strong and located entirely on the plantar face of the bone. The 

 phalanges have no rugose surface on their plantar sides for the attach- 

 ment of pads. The unguals are high and pointed. 



The Pelvis, Hind Limb and Foot. — (PL XIV. ) The pelvic region 

 in No. 562 is in fairly good preservation and differs but little from 

 that of O. longipes. The sacrum has five, instead of four, coossified 

 centra. The femur and tibia though smaller exhibit no important 

 differences, which is also true of the tarsals. The metatarsals of No. 

 664 are damaged proximally, but No. 562, which I have associated 

 with the type, has this region of the hind limb better preserved, and 

 shows the coossification of the palmar processes. Metatarsal II ad- 

 heres closely to metatarsal III, and metatarsal V is absent, thus ap- 

 proaching the llama rather than O. longipes. 



Measurements of Limbs. 



Greatest width of humerus at distal end 46 mm. 



Greatest height of trochlea at distal end 34 mm. 



Length of radius 284 mm. 



Width of radius at head 41 mm. 



Width of radius medially 31 mm. 



Width of radius distally 46 mm. 



Length of metacarpals 255 mm. 



Total length of femur, approximately 270 mm. 



Total length of tibia 328 mm. 



Total length of metatarsals 267 mm. 



Total length of proximal phalanx 55 mrn. 



Total length of median phalanx 28 mm. 



Total length of ungual phalanx 25 mm. 



OXYDACTYLUS COMPARED WITH OtHER LoUP FoRK AND LaTE 



Oligocene Genera. 



Procamelus differs from Oxydactylus in the absence of the first and 

 second pairs of superior incisors, and the union of the metapodials."' 



The genus Piliauchenia differs generically from 0\ydaciyIits by the 

 absence of the second inferior premolar. Protolabis has short limbs 



'^^ Some material in the American Museum of Natural History which is referred to 

 this genus has the rugose attachment for the pads on the plantar face of the phalanges, 

 and may have some relation to the genus Pliauchenia. 



