148 DK. J. MUEIE ON THE FOEM AND STEUCTUEE OP THE MANATEE. 



middle of the under surface of the third dorsal vertebra, aud the other to the under- . 

 side of the head of the second rib. At the cranium the muscle is fixed by fleshy fibre. 

 Portions of each longus colli tertius are exposed between the bellies of the recti antici 

 majores from the atlas backwards. 



(B) Those of the Skull or Cephalic Segment: Facial or Supracranial. — The three 

 muscles of the face respectively recognized by anthropotomists as the pyramidalis 

 nasi, the compressor nasi, and the dilatator itaris, each and all appear to be well 

 developed in the genus Manatus, notwithstanding that their fibres are indefinitely 

 united. In the remarkably deep but narrow hollow intervening betwixt the maxillary 

 bone and the nasal cartilage there lies a strip of muscular fibres, much intermixed, 

 however, with what appears to be fatty tissue. The fibres possess a partly transverse 

 and partly oblique direction. At the upper part the transverse muscular structure is 

 necessarily short, from the configuration of the parts, but forwards from this by degrees 

 lengthens, becomes more oblique, and as a thick bundle fills the bony depression above 

 the zygomatic!. Mesially situated, or upon the nasal cartilages, the fibres curve archedly 

 over the nares and meet those of the fellow muscle of the opposite side. 



I am inclined to regard the upper narrow but deep portion of this combined muscle 

 as homologous with the pyramidalis nasi (see fig. 12, P.n) — those fibres that cross the 

 naris, with the compressor nasi of human anatomy (figs. 10, 11, 12, C.n)- — and the most 

 anterior fibres, or those that deeply encircle the aperture of the nose, with the dilatator 

 naris {B.n, fig. 12). These last, moreover, appear to include those diminutive human 

 muscles styled the levator proprius alee nasi posterior and levator proijrius aloe nasi 

 anterior. 



The anomalous fibres of Albinus, or nasal rhomboideus of Santorini, may here be 

 represented by a longitudinal slip at the outer border of the above triadherent muscle. 

 The fibres of the said slip arise from the inner aspect and upper surface of the orbit, 

 and, running obliquely inwards and well forwards, mingle with the premaxillary portion 

 of the foregoing. 



Unless what has been taken as Santorini's rhomboideus is a displaced zygomaticus 

 minor, then there is present but one well developed zygomaticus muscle. This arises 

 from the deep infraorbital fossa, and is inserted into the tinterior portion of the naris, 

 there interblending with the depressor labii superioris alseque nasi. The infraorbital 

 arteries and. nerves, as might have been expected from the vast size of the muzzle, are 

 of large size, and lie alongside of and upon the zygomaticus muscle. 



A levator labii superioris proprius I identify in a broad fan-shaped or triangular layer 

 of muscle, which arises apically from underneath the projecting orbit, and expands 

 upon the sides of the nares, front of the muzzle, and upper lip. It is much shorter 

 than the layer covering it, but is equally fleshy, and rather the thicker of the two ; in 

 magnitude it is much greater than the zygomaticus, which it overlies and hides. A few 

 only of the fibres of the levator labii superioris proprius proceed towards and over the 



