COPE.] PALEONTOLOGY MIOCENE PERIOD. 499 



longitudinal angular ridge. The neural spine is a prominent keel of no 

 great elevation. The hypapophysis is an acute keel, low in front, but 

 produced downward and backward to a rugose, obtuse extremity. The 

 centra are slightly opisthoccelian ; the articular surfaces so moderately 

 interlocked as to constitute a form intermediate between that of the 

 camel's and of the Macrauclienia. An anterior dorsal vertebra is more 

 strongly opisthoccelian, resembling that of the llama. The diapo- 

 physis has a reniform tubercular surface, which looks downward ; from 

 its posterior-inferior angle, a strong, fold-like ridge originates, and is 

 continued as the posterior margin of the neural arch. Below the capit- 

 ular facet, a short ridge originates, which incloses a median fossa, with 

 its fellow on the anterior half of the centrum. A lumbar exhibits a 

 strongly-depressed centrum, and the absence of an epiphysis from it 

 and from the dorsal described indicate the immaturity of the individual. 



The humerus is a little expanded distally, and is truncate from the 

 trochlear margin on the inner side. The posterior portion of this face 

 is produced into a strong tuberosity, of which a trace may be observed 

 in the llama, which prevents the extension of the fore-arm beyond an 

 angle of 180°. The inner trochlear face has the greater sweep and less 

 width, and is uninterrupted ; the outer is wider, and is divided into two 

 nearly coincident planes. There is a supracondylar, but no arterial 

 foramen, as in Oreodon. 



The fore-arm is long and slender, and the ulna co-ossified its entire 

 length, except a foramen near its distal end. The medullary cavities of 

 the two bones are separated for the proximal half of their length. A 

 shallow groove distinguishes the ulna proximally, and at the middle of 

 the shaft the latter forms an acute edge. Distally, the combined bones 

 present three planes, two lateral and a median. The lunar facet is 

 most impressed ; the scaphoid and cuneiform are equally prominent. 



The carpus consists of eight bones, the entire mammalian number, ail 

 entirely distinct. The second series presents the most important i^ecu- 

 liarities. The trapezium is small and posterior ) the trapezo'ides has an 

 almost entirely lateral presentation, and is also small, and fits an angle 

 of the magnum ; the metacarpal facets of these bones are con- 

 tinuous and uninterrupted. The magnum is flat and transverse ; the 

 unciform is nearly as Inroad, and less depressed; it presents two inferior 

 articular faces, the lesser interior for the third metacarpal ; that for the 

 fifth metacarpal is wanting. 



There are two principal and two rudimental metacarpals. The third 

 articulates with half of the trapezoides, the magnum, and a fourth of 

 the unciform ; the fourth with the remainder of the unciform. The 

 second and fifth are very short and wedge-shaped, and closely adherent 

 in shallow fossae of the third and fifth respectively. The latter are dis- 

 tinct, and present no traces of present or i)rospective attachment; their 

 opposed faces are only flattened on the proximal three-fourths, and 

 rounded on the remaining fourth. Their articular extremities present 

 no basal ridge, and the median keel is posterior, terminating at the dis- 

 tal center. The basal phalanges are short, and with a dis.tal trochlear 

 groove ; those of the second series are half as long. 



Another specimen displays, in addition to cranium with teeth, vertebra;, 

 &c., the hind limbs. The astragalus is that of a true ruminant, but the 

 astragalus and cuboid bones are entirely distinct. The ectocuneiform 

 is a subcubical bone, and is distinct from the inner cuneiform behijud it, 

 and which is relatively larger than in the typical Euminantia. The 

 metatarsals are two in number, and are distinct throughout their length, 

 the distal portions being not even flattened for mutual contact. They 



