DR. J. MURIE ON THE ORGANIZATION OF THE CAAING WHALE. 273 
What constitutes the pectoralis major in Cetaceans is a moot point. Cuvier, in his 
Legons’, says, “Dans les mammiféres qui n’ont point de clavicules parfaites, méme 
dans le dauphin, il y a une premiére portion sternale qui va perpendiculairement a la 
ligne apre, et qui forme avec la portion correspondante de l'autre cété, ce que Yona 
appelé le muscle commun aux deux bras; c'est lui qui produit l’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 Rapp‘ 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 Tiimmlers,” 7. ¢. p. 16. * Op. cit. p. 89. 
® Fréd. 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 (Rapp, 89). 
