140 THE VOYAGE OF H.M.S. CHALLENGER. 



Rosenthal, F., Ueber die Sinnesorgane der Seehunde. Nova Acta Acad. Cmes. Leqp.-Carol., 1831. 

 Humphry G. M., On the Myology of Orycteropus capensis and Phoca communis. Journ. Anat. and 



Physiol, May 1S6S. 

 Murie, J., Upon the Anatomy of the Pinnipedia. Trans. Zool. Soc. Lond., vols, vii., viii. 

 Lucae, J. C. G., Die Robbe und die Otter. Abhandl. Senckmberg. Naturf. GesellscK, 1873-75. 

 Cunningham, D. J., Report on some points in the Anatomy of the Thylacine (Thylacinus cynocephalus), Cuscus 



(Phalangista maculata), and Phascogale (Phascogale calura), collected during the Voyage of H.M.S. 



Challenger in the years 1873-1876; with an account of the Comparative Anatomy of the Intrinsic 



Muscles and the Nerves of the Mammalian Pes. Zool. Chall. Exp., vol. v. part xvi. 



Deemal Muscles. 



The Panniculus carnosus in Phoca vitulina is an extensive sheet of subcutaneous muscular fibres 

 subjacent to pelt, blubber, and the deep fascia, which is dense and coarse in some regions, fine and 

 transparent in others. Dorsally, the panniculus almost covers the axial part of the animal. It 

 stretches from above the orbits to the root of the tail, ending as two finger-like prolongations 

 between the tail and the dorsal surface of the legs. Upon the ventral aspect, it begins at the 

 lower lip, covers all the neck, recedes from the presternum, exposing a small part of the sterno- 

 mastoid and cephalo-humeral muscles ; overlaps the pectoral, 1 with the exception of a margin near 

 the sternum, and extends almost longitudinally, from the side of the thorax to the femur, which 

 it crosses midway between the trochanter and the external condyle, to join the finger-like pro- 

 longations. The belly, therefore, wants a subcutaneous muscular layer, and the abdominal part of 

 the pectoral and the external oblique lie next the investing fascia. 



It is capable of division into five parts by the direction of the fibres : — a. The Platysma, on 

 the ventral side of the neck. b. The Lateral cervical, between the platysma ventrally and the 

 cervico-scapular dorsally. c. The Pectoral, on the sternal pectoral muscle, d. The Cervico-scapular 

 covers the back of the neck, and stretches from the orbit to the spine of the scapula, e. The 

 Dorso-abdominal extends from the scapular spine to the tail. 



a. The Platysma is pale, and covers the muscles between the rami of the lower jaw, and 

 extends backwards to the junction of the presternum with the meso-sternum. The fibres are 

 longitudinal where they spring from the side of the presternum, but turn outwards at their anterior 

 ends ; some of these terminate over the sterno-mastoid, and partially overlap it near its insertion. 

 The remainder become more and more obliquely directed outwards ; at the anterior termination of 

 the presternum they become transverse, and over the thyroid cartilage also are transverse. The 

 most posterior fibres join the lateral cervical part ; all in front of these terminate after passing 

 over the ramus of the lower jaw, by mingling with the fibres of the lateral cervical, round the angle 

 of the mouth, and insert themselves into the skin round the lower lip. 



b. The Lateral cervical is also pale, and passes forwards from the side of the neck. It begins 

 over the cephalo-humeral and sterno-mastoid muscles near their insertions. The fasciculi ascend 

 to the angle of the mouth, the lower lip, and the zygoma, where they end. The sides of this 

 longitudinal band are joined dorsally by the cervico-scapular part, and ventrally by the platysma. 



c. The Pectoral is fan-shaped, and rests upon the presternal and sternal parts of the pectoral 

 muscle, which originate from the presternum and meso-sternum. The inner margin of the fan 



1 Only one specimen had a pectoral panniculus. 



