384 DU. B. C. A. VriXDrjE A\t) Mn. F. ft. PAHSOIfS OK THE [Apr. 6, 



the same animal ; still, so far as our observatious go, the four-la^'ered 

 muscle is the most generalized type and corresponds to the human 

 three-layered pectoralis major aud the pectoralis minor. The 

 above description corresponds as closely as can be expected with 

 Allen's Procijoii lotor (XXVI.). Frocyon cancrivorus (57) agrees 

 with P. lotor except that /3 is inserted largely into the shoulder 

 capsule, while o was not distinguished. The Mustelidae resemble 



Fig. 7. 



"- PacTOKffi/i, 



PfCT.qa/r/ii 



^^yv^/ci/i.'/dit^. 



Pectoral muscles and pannicnlus of Lutra vulgaris. 



the Procyonidffi in the feeble development of the pectoralis quartus 

 (see fig. 7) ; in some animals, however, e. g. Proteles (25), this part is 

 much more marked, rising from a considerable distance back along 

 the linea alba and being connected by the panniculus to the latis- 

 simus dorsi in such a manner that the floor of the axilla is quite 

 closed in by muscidar fibres. In the Hyaenidas the muscle is very 

 strong and is inserted into the whole length of the humerus: 

 moreover it does not appear to be as broken up as in other Car- 



