EPICONDYLAR FORAMINA 



39 



the former is alone concerned with the glenoid cavity. It must 

 therefore, one would suppose, correspond to the " coracoid " of the 

 Monotreinata, while the upper piece of bone is the epicoracoid 

 process of that mammal. The Mammalia, therefore, higher as 

 well as lower, differ from the reptiles in that the coracoid is 

 formed of two bones, the exceptions being, among some other 

 extinct forms, certain of the Anomodontia, a group which it will 

 be recollected is the nearest of all reptiles to the mammals. 



The Fore-limb. The humerus is of varying length among 

 mammals. A feature which it sometimes shares with the humerus 



FIG. 30. Distal extrem- 

 ity of the humerus to 

 show Epicondylar Fora- 

 mina. A, In Hatteria ; 

 B, in a Lizard (Lacerla 

 ocellata) ; C, in the 

 Domestic Cat ; D, in 

 Man. c.e, External con- 

 dyle ; c.i, internal con- 

 dyle. In A the two 

 ' foramina are developed 

 (at i, the entepicondy- 

 lar ; at ii, the ectepi- 

 condylar). The only 

 canal (f) present in the 

 Lizard (B) is on the 

 external ulnar side, in 

 the cartilaginous distal 

 extremity. In Man (D) 

 an entepicondylar pro- 

 cess (pr) is sometimes 

 developed and con- 

 tinued as a fibrous band. 

 (From Wiedersheim's 

 Anatomy of Man. ) 



of lower forms is the presence of an entepicondylar foramen, a 

 defect of ossification situated above the inner condyle of that bone 

 which transmits a nerve. The same foramen and an additional 

 ectepicondylar foramen are found in the ancient reptilian type 

 Hatteria (Sphenodon) ; it occurs also in the Anomodont reptiles. 

 It is as a rule only the lower forms among mammals which show 

 this foramen ; thus it is present in the Mole and absent in the 



