164 DE. J. MUEIE ON THE FORM AND STRUCTURE OF THE MANATEE. 



2^ inches broad and IJ inch thick at this point); thence it passes forwards and out- 

 wards (P.(f) on the neck, beneath the platysmal cross fibres, ultimately being inserted 

 as a broad and strong tendinous sheet into the malar bone, posteriorly and interiorly to 

 the first portion of the panniculus, as already detailed. 



Superficial to the shoulder and sternal segments, and as it were forming a bridge 

 between them in front of the pectoral extremity (P.c^), is what appears as a platysma 

 myoides. This is represented by a coarse thin sheet of muscle interspersed with much 

 fatty tissue. The fibres may be said to arise from the inferior median surface of the 

 neck and mandible for several inches in breadth, intermingling there with those deeper 

 segments of the panniculus mentioned above. Crossing the neck in a transverse direc- 

 tion, the fibres radiate slightly, and are firmly but superficially intertwined with those 

 of the lower border of the outer nuchal panniculus, whilst fibrous tissue and fat connect 

 them with the infraspinatus. A narrow slip of the muscle extends downwards on the 

 anterior border of the limb as low as the middle of the biceps, whence, becoming 

 fibrous, it descends as a cord-like body as far as the base of the metacarpal bone of the 

 first digit (P.c'*, fig. 13). 



At the anal or posterior end the fibres of the panniculus diverge triradially (P.c***), 

 a broad portion curving gently outwards ; and the intermediate portion (larger) ends 

 wedge-shaped with inwardly inclined fibres, which, along with its fellow of the opposite 

 side, are inserted by strong aponeurosis between the depressores caudae into the sixth 

 chevron bone. 



In the female there was also observed another fleshy slip, about an inch broad, which 

 was given off" from the body of the muscle opposite the generative outlet; and this 

 proceeded downw^ards and backwards, being likewise inserted into the skin on the 

 median perineal region. 



Connected with the action of this subdermal muscle it may be remarked that, as in 

 Cetacea, it can have little or no power over the skin itself, not being fastened thereon, 

 a thick coating of fat intervening. On the other hand the attachments of the muscle 

 point to its subserving the bodily force of various parts. For instance, the fixed points 

 to the malar bones must give the advanced segment of the muscle a very long leverage 

 for movements of the head ; at the same time the insertion on the facial bones and lips 

 must lend power to the labial muscles, and in some ways act as a dilatator oris, and 

 impart additional strength to the thick muscles of the great muzzle. 



V. The Digestive Tract. 



1. Interior of the Mouth, and Tongue. 



The very curious structure of both the exterior and interior parts of the mouth has 

 been a favourite topic of those who have contributed memoirs on Manatus. Stannius's 

 account is, on the whole, the most explicit, though brief. In treating of the mandu- 



