DR. J. MUEIE ON THE FOEM AND STEUCTUEE OF THE MANATEE. 153 



standing, is present, though greatly reduced in size. It arises as usual from the 

 manubrium, but in front of the pectoralis major. Hence with a diminutive thin flat 

 muscular belly, 3 inches long and ^ an inch broad, it proceeds forwards anteriorly to 

 about a level with the outer border of the scapula, where it bifurcates (see fig. 9, St.m). 

 The outer limb, a thin, strong, round tendon (shown in figs. 29, 30, St.m), pierces the 

 substance of the parotid gland, and is inserted into the paramastoid ; the inner fork, a 

 broadish aponeurosis, joins the deep cervical fascia of the neck, supei-ficial to the carotid 

 artery, and posterior to the thick fleshy digastric muscle. The shortening of the neck, 

 great vascular rete, &c. give peculiar relations to the parts in the Manatee. 



From the unusually fiat and wide arched form of the ribs, the serratus magnus muscle 

 appears to have a difiiereut position from what it has in deep-chested animals, though 

 in reality it departs little, if at all, from its normal situation ; it is nevertheless com- 

 paratively short and thin. The costal attachments are from the sixth rib forwards. 

 On the scapula it is fixed underneath the rhomboideus the whole length of the 

 vertebral border and to a triangular corner of the posterior inferior angle for about an 

 inch in extent. Anteriorly in firm connexion with the fleshy scalene muscle it extends 

 forwards, and is inserted into the outer and posterior surface of the enlarged transverse 

 process of the atlas {S.mg, fig. 29). The nuchal portion of the muscle has a twist upon 

 itself, and is overlain by the broad belly and insertions of the scalenus, so that only a 

 small segment of it is seen on the ventral surface of the neck when the parts are 

 examined in position. 



The serratus in the Elephant' is very massive, and extends backwards to the tenth 

 or eleventh rib. MeckeP says it is very small in Cetaceans, only fixed to at most four 

 ribs ; but my own researches agree rather with Carte and Macalister^ and partly with 

 Stannius*, in their being an apparent tmsting or duplicity of the muscle and greater 

 costal attachment. 



The latissimus dor si, as in the Cetacea, is entirely hidden by the superimposed layer 

 of the panniculus, and it itself overrides in part the costal portion of the serratus 

 magnus. On the surface of the chest it presents a broadish fan-shaped fleshy 

 expansion, relatively short, upon the ribs from the fourth to the eighth ; there is a 

 deficiency of tendon or fascia at this costal attachment, the muscular fibres being well 

 defined, and reaching no higher than on a level with the post-inferior scapular angle, 

 below the sacro-Iumbalis. It continues fleshy anteriorly to where it joins the teres 

 major, the two muscles (as mentioned further on) being fixed together [La.d, fig. 8) to 

 the middle of the shaft of the humerus. 



Abdominal. — Previous observers concur in noting the strange reptilian-like lengthening 

 of the lungs and diaphragm, and consequent relatively altered position of the heart and 

 upper or anterior abdominal viscera in Manatus; the same obtains in the two other 



> PI. 207. 9. " Vol. vi. p. 246. ' Memoir, p. 224. 



* Under serratus anticus major, I. c. p. 13, and Eapp. p. 89. 



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