144 PROCEEDINGS OF THE ACADEMY OF [1888. 



taches to the outside of the great tuberosity and partly reaches the 

 surface of the supra-spinatus muscle and the coracoid process. It is 

 between this muscle and the involuted fold of the p. major that the 

 deep anterior thoracic nerve issues. 



Beneath the anterior portion of the pectoralis major and superficial 

 to the p. minor, lie two muscular ribbons. The more anterior {sterno- 

 scapularisf) rises for \\ inches on the manubrium and inserts, ante- 

 riorly by fascia and posteriorly by muscular fibres, into the great 

 tuberosity and bicipital ridge for a distance of 3 inches. It thus 

 increases in width outwards. The other band lies immediately 

 posterior to this in the same plane, rising on the first three sternebrie ; 

 anteriorly it is quite distinct from the p. major, but its posterior 

 border fuses more or less with the latter. Its anterior fibres have an 

 independent insertion on the bicipital ridge, while posteriorly it 

 inserts in common with the p. major and cephalo-humeral. 



The diverse ideas concerning the homologies of the pectoral ele- 

 ments, and the consequent confusion of nomenclature are well-known. 

 In the Carnivora, for instance, Cuvier^ denies the existence of a 

 pectoralis minor— though as remarked by Murie, the " Planches de 

 Myologie " of Cuvier and Laurillard represent it as present ; this 

 opinion is supported by MeckeP and many recent investigators. 

 Others who admit the presence of the muscle differ considerably in 

 the element to which they apply the name. Wilder^ believes the 

 superficial backwardly directed layers to be the pectoralis major, 

 and all of the deep forwardly directed bands, with apparently the 

 exception of the most posterior (" xiphi-humeral ") to be homologous 

 with the human pectoralis minor. Owen* seems to consider that in 

 the dog only the most anterior of these deep bands represents the 

 p. minor, while Shepherd^ applies the name to the muscle which has 

 here been described as sterno-scapular. 



The muscle which I have described as the pectoralis minor appears 

 to me to be such, not only in the bear, but throughout the Carniv- 

 ora, from its general position, from the usual continuation of its 

 fascial insertion to the coracoid process, and from its relations to 



1 Lemons d'Anat. Comp. Tome 1, p. 256. 

 Syst. vergleich. Anat. Theil 3, pp. 49(1-1. 



2 The Pectoral Muscles of Mammalia. Proc. Am. As. Ad. Sci. 1873, p. 3U7- 



Also, Anatomical Technology, p. 235. 

 * Anat. Vert. Vol. Ill, p. 50. 

 5 Loc. Cit. p. 105. 



