430 THE EOCENE PEEIOD. 



of the column. The number of the caudal vertebrae is not known, but 

 they were numerous. 



The transverse process of the axis is shoil and flat, and not narrow as 

 in lapirus, and its base is perforated posteriorly by the vertebrarterial 

 canal. The latter issues on its inferior face, and perforates the neural arch 

 transversely just above the superior border of the cotylus for the occipital 

 condyle. The axis has a cylindric odontoid, and atlantal facets well sep- 

 arated. Its neural spine is well developed. A vertebrarterial canal. The 

 articular faces of the succeeding cervicals are oblique and slightly opisthoc- 

 oelous. The transverse processes are narrow, are directed posteriorly, and 

 have no descending processes except on the sixth centrum. Seventh cervi- 

 cal without vertebrarterial canal. The second dorsal has rather elonerate 

 diapophyses without metapophyses ; the neural spine is nan-ow and rather 

 elevated. The metapophyses are quite elevated on the posterior part of the 

 series, and the centra become somewhat opisthocoelous and depressed. No 

 anopaphyses on either dorsals or lumbars. The latter have well-developed 

 flat diapophyses, and the centra are keeled below. The postgygapophyses 

 are not revolute, but they become oblique, so that the external parts of the 

 surfaces are nearly vertical. The centra of the sacrum are rather elongate, 

 and are of equal length. The diapophyses of the first sacral are short and 

 deep, and present no articular facets for the diapophyses of the last lumbar. 

 The iliac articular surface extends over the first and part of the length of 

 the second sacral vertebrae. The rest of the sacrum has united diapoph- 

 yses continuous with it. The caudal vertebrae were probably numerous, 

 the proximal have strongtransverse processes, and the median are robust 

 in the P. primcevus. Some of them have chevron bones. 



In the ribs the capitular and tubercular facets are well developed. The 

 shafts are flattened excepting at the posterior part of the series. The epis- 

 ternum is elongated and compressed, and it has two costal articular facets 

 near its middle. The anterior sternal segments are narrow; the posterior 

 are wider and flattened. No clavicle. The scapula is widened anteri- 

 orly as in the ursine Carnivora, the Amblypoda, and the I'roboscidea, and has 

 a short coracoid process. The spine rises abruptly from the neck, and 

 turns forward in a strong acromion. '^I'lie tuberosities of the humerus are 



