CHIONIS MINOR. 93 



lower border and about one-half the lateral surface of carina ; and 

 from the posterior and external third of the body of sternum, to be 

 inserted by a broad fiat tendon into the palmar margin of the pectoral 

 crest of humerus. The pectoralis major is partly cleft, posteriorly and 

 inferiorly, but the two parts coalesce to be inserted b}^ a single tendon 

 as above. 



Second pectoral arises from sternoclavicular membrane, from the 

 angle between the body and keel of sternum to within 0.25 inch of its 

 l^osterior end, and from all of the body not occupied by the conjoined 

 segments of pectoralis major. It is inserted by a very long cylindrical 

 tendon, gliding through a tendinous sheath given off from the neighbor- 

 hood of coraco-clavicular articulation, beneath the angle of their junc- 

 tion, into radial tubercle of humerus, 0.50 inch below its articulating 

 surface. This is the levator humeri. 



Third pectoral {'-'' pectoralis minimus''' Coues*) arises fleshy, pyram- 

 idal, from external border near superior external angle of sternum 

 and from the adjoining margins of sternum and coracoid, for about 

 one-third their length, to be inserted by a round tendon directly into 

 inner border of humerus, near its head. In origin and function this 

 muscle agrees with pectoralis minimus of Coues, and of Owen, 1836 

 (but not with third pectoral of Owen, 1866, being an adductor and 

 external rotator but not a levator of humerus; arising from external 

 border, not angle, of sternum ; and passing through no trochlear groove, 

 but being inserted by a straight tendou into radial tuberosity of 

 humerus, which it depresses, not elevates). 



The article in Todd's Cyclop. Anat. describes the third pectoral- 

 substantially as it is here given ; but in Anat. Vert., ii, 18G6, p. 97, 

 apparently by some oversight, Professor Owen redescribes the third 

 pectoral in much the same terms as he does the second, making it 

 out to be a levator. 



Latissiinus dorsi shows no peculiarity of origin or insertion. Ante- 

 rior libers are a thin narrow band of pale muscle. Posterior are darker, 

 stouter, and blend, before insertion, with anterior. A few muscular 

 fibers pass downward from steroo-coraeoid articulation, parallel with 

 sternal ribs. 



Extomor plicce alaris arises from coraco-clavicular articulation, send 

 iug its tendon downward along the pectoral ridge of humerus. It is 

 triangular in form, covering the rest of the muscles of the shoulder- 

 joint. Just beneath it lies the — 



* Odteology, etc., of Colymbus torquiitus, Mem. Bost. Sue. Nut. Hist, i, 18i38. 



