148 DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 
middle of the under surface of the third dorsal vertebra, and 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 naris, 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 zygomatici. 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.v)—and the most 
anterior fibres, or those that deeply encircle the aperture of the nose, with the dilatator 
naris (D.n, fig. 12). These last, moreover, appear to include those diminutive human 
muscles styled the levator proprius ale nasi posterior and. levator proprius ale 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 foregcing. 
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 anterior portion of the naris, 
there interblending with the depressor labii superioris aleque 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 1 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 
