DE. J. MURIE ON TKE ORGANIZATION OF THE CAAINa WHALE. 273 



What constitutes the pectoralis major in Cetaceans is a moot point. Cuvier, in his 

 Lemons', says, "Dans les mammiferes qui n'ont point de clavicules parfaites, meme 

 dans le dauphin, il y a une premiere portion stemale qui va perpendiculairement a la 

 ligne apre, et qui forme avec la portion correspondante de I'autre cote, ce que Ton a 

 appele le muscle commun aux deux bras ; c'est lui qui produit I'entre-croisement des 

 jambes de devant." It is evidently this same portion which Meckel^, with whom 

 Rapp^ coincides, refers to as an elongated strong triangle, partially continuous with 

 the panniculus, and inserted broadly into the humerus as far as the antibrachial 

 aponeurosis. Stannius *, however, views it differently, regarding this only as a thoracic 

 portion of the panniculus; and the true pectoralis major he specially points out to be 

 what Eapp* and, possibly, Meckel have considered the pectoralis minor. There may 

 be some good grounds for the conclusion which Stannius has arrived at, that the 

 deeper portion is pectoralis major and not pectoralis minor, if it is allowed, there are 

 two layers of the former, which to some extent obtains in Ruminants and Rodents. 

 On the other hand, the superficial layer ought certainly not to be confounded with the 

 thoracic portions of the panniculus ; for neither in the direction of its fibres, at nearly 

 right angles to this last, nor homologically traced in other Mammals, does it positively 

 belong to it. 



For these reasons I shall therefore describe the pectoralis major in the Pilot Whale 

 as a somewhat broad and rather triangularly shaped muscle, arising upon the superficies 

 of the thorax from opposite the fourth to the first rib, meeting its fellow in the median 

 line over the sternum'. Its fibres are directed outwards and slightly forwards, and 

 are inserted by strong aponeurotic tendon into the breadth of the distal end of the 

 humerus. The fibres of the panniculus, as already mentioned, intermingle with those 

 of its posterior border, while anteriorly the representative of the platysma is similarly 

 related. The description of pectoralis major in B. rostrata'' pretty closely agrees with 

 the above ; and in other Cetaceans examined by myself little difference obtained. 



If the pectoralis minor is not, as hinted at, a deep layer of the pectoralis major, then 

 I may assume that in Globiceps it has an origin from the ventral surface and median 

 line of the thorax over the sternal cartilage of the fourth rib. Only of moderate 

 breadth, but long, it is inserted into the strong fascia at the inner posterior root of the 

 flipper. A muscle equivalent to the above existed in L. albifrons, but was attached as 

 far as the sixth costal cartilage. In the Porpoise, Stannius^ notes the pectoralis minor 

 as short and fleshy, springing from the anterior border of the sternum, behind the 



' D'Anat. Comp. 2nd ed. (1835), vol. i. p. 393. 



' Op. cit. p. 269. ^ " Die Cetaceen," p. 90. 



* " Muskeln des Tummlers," I. c. p. 16. ' Op. cit. p. 89. 



' Fred. Cuvier speaks of it as the " musculus communis," Cyclop, of Anat. & Phys. vol. i. p. 571. 



' Carte and Macalister, p. 218. 



' L. c. p. 14 (Eapp, 89). 



