1916] Holliger: Anatomical Adaptations in the Pocket Gopher 475 



pi. 39). The tendon passes down under the coraeoid process of the 

 scapula, and is inserted on the lesser tuberosity of the humerus. 

 The subscapularis is a flexor and adductor of the leg. 



21. Triceps hrachii {tri., fig. S). This muscle is relatively 

 more important in the quadrupeds than in man, since it must 

 support a considerable part of the weight of the body in standing. 

 And it is especially well developed in fossorial forms, in which it 

 furnishes nearly all of the power for extending the forearm, a 

 very important movement in digging. All three heads of the tri- 

 ceps are strongly developed in the gopher. 



a. Caput longum arises from the distal three-fourths of the 

 lateral surface of the axillary border of the scapula {tri. long., 

 pi. 38). This is the bulkiest of the three parts, and its insertion is 

 nearest the end of the olecranon process. 



&. Caput later ale arises from the posterior and lateral surfaces 

 of the humerus in a line extending from a point just below the 

 head down to the deltoid tuberosity {tri. lat., pi. 38). It is inter- 

 mediate in volume, and its insertion is on the lateral surface of the 

 olecranon process and on the fascia over the origins of the extensor 

 muscles of the hand {tri. lat., fig. Q). 



c. Caput mediate {tri. med., fig. T) arises from the posterior 

 and mesial surfaces of the humerus from a point just below the 

 lesser tuberosity nearly to the distal extremity of the bone. Its 

 insertion covers most of the cephalic surface of the olecranon 

 process. 



22. Extensor antihrachii parvus or epitrochlearis {ex. ant. par., 

 fig. T ) is a slender, flat band of muscle fibers arising from the 

 fascia of the teres major and latissimus dorsi, and inserted on the 

 tip of the mesial border of the olecranon. It is a weak extensor 

 of the forearm. 



23. Anconeus medialis {anc. med., fig. T) arises from the pos- 

 terior surface of the internal supracondylar ridge of the humerus, 

 to be inserted on the mesial surface of the olecranon process {anc. 

 med., pi. 39). 



24. Anconeus lateralis {anc. lat., fig. S) arises from the pos- 

 terior surface of the external supracondylar ridge of the humerus, 

 and is inserted on the lateral surface of the olecranon near its tip. 

 The anconei are weak extensors of the forearm; the anconeus 

 lateralis is the smaller of the two and is not found in the rabbit. 



