DB. J. MUEIE OX THE POUM AND STETJCTUEE OF THE MANATEE. 145 



exoccipital bone, betwixt the cephalo-humeral and the complexus muscles ; the united 

 superior obliquus and the rectus lateralis are situated below and within. 



The splenius and complexus appear almost a continuation of the long internal spinal 

 muscle ; there is, however, a distinct separation, excepting a few of the fibres. Of 

 the two the splenius {Sp, fig. 8) is much the smaller. It diverges, so to speak, from 

 the fleshy fibres of the complexus outwardly, opposite the second rib, and proceeds 

 broadly to the skull, where it is inserted by a short, flat, but very strong tendon into 

 the exoccipital ridge above and behind the cephalo-humeral. The larger, thick and 

 long complexus arises from the outer side of the spinalis dorsi, above the head of the 

 sixth rib. It covers the remaining interspace between the ribs and the compressed 

 anterior portion of the spinalis dorsi forwards to the cervical vertebrae, where it spreads 

 out and lies superficial to the short recti and oblique muscles. It is inserted into the 

 whole of the back of the cranium, as far outwards as the paramastoid. 



The short deep muscles of the back of the neck are well represented, in spite of the 

 diminution of the posterior cervical vertebrae ; for the atlas and axis are still of fair 

 dimensions. They show no deviation in attachments from those of ordinary mammals. 

 The rectus capitis posticxis major and minor have coalesced fleshy fibres, the former being 

 much the larger of the two. The obliquus inferior is well developed, and somewhat 

 fusiform. The obliquus superior and rectus lateralis are closely united, and together 

 form a short fleshy band. 



These posterior short muscles of the neck Stannius' partly treats along with the 

 semispinales in the Porpoise ; but in the Pilot Whale, Macalister^ and myself have both 

 found a very large rectus posticus, apparently major and minor. I have also defined 

 obliqui in the same animal. In the Elephant' there are a distinct voluminous rectus 

 capitis major, an obliquus superior, and obliquus inferior obtain. 



Ventral Aspect. — Before drawing attention to the descriptions and opinions of Rapp 

 and vStannius concerning the presence and homologies of the infralumbar and subcaudal 

 muscles of the Dolphin and Manatee, I deem it preferable to lender an account of my 

 own dissection of the parts in question. In Manatus five, or at least four, distinct 

 muscular masses can be traced without difficulty, as superimposed in two broad flattish 

 layers, with an additional lateral or outlying fusiform one. 



The first and notable muscle is that which in the profile and under-view appears as a 

 great and the only mass filling the interval between the last rib and the caudal extre- 

 mity, and the space between the chevTon bones and the tips of the lumbo-caudal 

 transverse processes. This aspect is in some respects deceptive, as the muscle, when 

 manipulated by the scalpel, is found to be only one of two thick and long layers 

 occupying the area in question. The superficial stratum or musculo-tendinous lamella 

 arises from the outer half and inferior surface of the last rib, being here partially 

 overlain by the external oblique and panniculus ; thence, with inwardly oblique fibres, 



' Loc. at. p. 30. - P. Z. S. 1867, p. 48] . = Myologie, pi. 282, lettered W, N, and N'. 



z2 



