566 



CHORD ATA, 



progressive changes, be noticed the gradual assumption of a 

 digitigrade method of walking from the primitive planti- 

 grade. Special allusion has been made to most of these 

 points in dealing with the horse and ox. The intestine is 

 always long, the uterus is usually of the bicornuate type and 

 the placenta is non-deciduate and either zonary, diffuse, or 

 cotyledonary. 



SUB-ORDER I. CONDYLARTHRA. 



The members of this sub-order are all extinct and they 

 represent the very lowest point of the ungulate stock. They 

 have the typical eutherian dentition of f ||^f and the molars 



Fig. 386. — Lateral View of Skull of Daman 

 {Hyrax syriacus). 



Note the rodent-like incisors, absence of canines and long row of seven 

 grinding premolars and molars. The malar bone is seen to extend 

 back to the glenoid cavity. 



were of simple brachydont structure. The limbs were planti- 

 grade, with five toes, and the carpal and tarsal bones were 

 serial. The fibula and ulna were not reduced, though the 

 latter had already lost its connection with the calcaneum. 

 The femur had a third trochanter, as in vaodtrnFerissodactyla. 

 The tail was long. The humerus, contrary to that of other 

 Ungulafa, had an entepicondylar foramen, resembling that 

 of Carnivora. The toes appear to have borne blunt claws 

 rather than hoofs. Phenacodus is the best known genus 

 to which the modern horse, and hence Perissodactyla, can 



