274 SHOULDER-GIRDLE IN MONOTREMES, 



is called dermo-humerien : the dermo-dorsi cervicalis is called 

 doiso-occipitien ; other parts are called portion dorsal, lateral, 

 ventrale ; on Plate 267 a dissection is shown of the slips going to 

 the hyoid, and is called " thoraco-facien," while a note says 

 r + + " Faisceau qui se detache de la partie posterieure de la 

 poche, et qui se parte transversalenient a I'os hyoide." 



Mm. pectoralis major et quartus. 



Echidna : P. majors Mivart ; P. major, anterior and j)osterior portions, 

 Westling, Leche. , 



Orn'ithgrhynchus : P. major includes clavicular portion of deltoid, Meckel, 

 Owen, Coues, Leche, Westling, Cuvier, and Laurillard ; P. major et P. 

 quartus, S. Smith. 



Pectoralis major. 

 Echidna. 

 Origin. This muscle arises from the posterior two-thirds of 

 the ventral surface and border of the interclavicle ; from the pre- 

 sternum, and mid-line of the mesosternum ; and the anterior half 

 of the ventro-lateral aspect of the raetasternum ; also from that 

 portion of the sternal extremity of the second to the seventh rib 

 (inclusive), that lies internal to the rectus. 



Insertion. The anterior fibres of the muscle run directly 

 outwards, the more posterior fibres run forwards and outwards, 

 the muscle being inserted by a well marked tendon on the ventral 

 portion of the external aspect of the greater tuberosity ; having 

 the epicoiaco-humeral internal to it, while the cleft tendons of the 

 pectoralis quartus and panniculus bound it anteriorly, distally, 

 and posteriorly (Fig. 3, Pt. M.). 



Relations. The anterior border of the muscle is separated 

 from the clavicular deltoid by a slight interval in which there are 

 some branches of blood vessels, and a small cutaneous branch of 

 the N. supracoracoideus. More externally the clavicular deltoid 

 hides from view the anterior edge of the pectoral. Along the 

 mid-ventral line its origin is hidden, in great part by the sterno- 

 mastoid, whilst it is separated from its fellow of the opposite side 



