292 MAMMALIA. 



Formation of New Mexico. Teeth very similar to those of Phenacodus are 

 also known from the Upper Eocene of Switzerland. 



Sub-Order 2. Hyracoidea. 



The small surviving hyraces (Hyrax or Procavia, and Den- 

 drohyrax) of Africa and Syria are generally believed to be the 

 little- modified descendants of the Condylarthra ; but no extinct 

 genera of the sub-order HYRACOIDEA, to which they belong, 

 have hitherto been identified with certainty. A typical skull 

 from the Lower Pliocene of the Island of Samos has been 

 recorded under the name of Hyrax kruppi. It is also curious 

 that a fossil skull exhibiting a close resemblance to that of 

 Hyrax has been obtained from the Pyrotherium Formation 

 (probably early Tertiary) of Patagonia. This is named Archceo- 

 hyrax patagonicus. The outer digits in the existing animals 

 are reduced or wanting. The carpal bones of the two series 

 are scarcely if at all alternating, and there is a distinct cen- 

 trale below the scaphoid. 



Sub-Order 3. Amblypoda. 



Before the close of the Eocene period the Ungulata with a 

 diminutive smooth brain attained their maximum develop- 

 ment and became extinct. Many of these animals attained a 

 remarkable size, some nearly as large as an elephant, and their 

 limbs became very robust to support the ponderous trunk. 

 They are generally grouped together in a sub-order named 

 AMBLYPODA (blunt feet) or AMBLYDACTYLA (blunt toes), in 

 allusion to their short and stumpy five-toed feet. The teeth 

 are brachyodont, with the tubercles more or less fused into 

 transverse ridges (thus technically described as lophodont) ; and 

 they are never more than the normal 44 in number. All the 

 vertebral centra exhibit flattened articular ends, and none of 

 the zygapophysial facettes are curved. The humerus has lost 

 the entepicondylar foramen, while the femur loses its third 

 trochanter in the most specialized genera. The ulna and fibula 

 are well developed. The feet are complete, small, and very 

 stout, becoming slightly digitigrade. The two series of carpal 

 bones scarcely alternate ; but in the tarsus the broad, depressed 



