DR. J. MURIE ON THE FORM AND STRUCTURE OF THE MANATEE. 201 
within the chevron bones; Z.Rete, lumbar vascular rete shown in part; Be, brain- 
cavity; n.ch, nasal chamber leading by narrow canal to n, external narial orifice ; 
Pmx, premaxillary bone in section, covered by the fleshy, fibrous snout; sy, mental 
symphysis; w/, upper lip (=outer); wp, upper pad (=inner lip); J/, lower lip 
(=outer); Jp, lower pad (=inner lip); 0h, buccal hairs; 7, tongue; Eus, orifice 
of Eustachian tube; Sgh, stylo-glossus and hyoid muscle; a double-headed arrow 
beneath leads from the fauces to the cesophageal and laryngeal passages, each 
partially laid open; /a,cut larynx; @, esophagus ; Rete &c, portion of rete cervicale ; 
J & C, jugular vein and carotid artery severed; I & F, muscle and fat between the 
fore limbs; cv, cervical vertebre. 
Fig. 38. Front segment of the skull, showing the nasal cartilage on the right side, and 
the open nares, diminutive nasal bone, &c. on the left. 
Fr, frontal bone; Na, left nasal; Tw, turbinals; O, right orbit; nc, nasal cartilage ; 
sp, septal cartilage ; cf, cartilaginous fissure ; Px, infraorbital plexus of arteries. 
Fig. 59. A transverse section of the tail behind the anal constriction, but in advance of 
the caudal expansion. It shows:—c, centrum of a vertebra, its articulating 
surface surmounted by the neural arch (a) enclosing the spinal cord, which 
is surrounded by a vascular plexus; ¢, cut surface of transverse process, 
between which and centrum is another rete mirabile; ch, lamina of chevron 
bone enclosing subcaudal rete; Lect, Lce, levatores caude internus and ex- 
ternus or continuation of the dorsal muscles; J.c, lumbo-caudalis ; Sc and 
If.c, sacro-coccygeus and infra coccygeus, lower tail-muscles; Sh, skin, fatty 
fibro-fatty layer, &c. 
Fig. 40. A cross section of the flat expanded tail: vt, vertebra; ¢’, levator caudal tendons, 
and ¢*, depressor caudal tendons surrounding the bone; f, fatty and fibrous 
tissue, containing the open mouths of nourishing vessels; sk, skin, its fibroid 
subdermal layer, covered by a black line representing the derm and cuticular 
covering. 
Fig. 41. A portion of the root-end of the lung, with its vessels minutely injected: 
B, bronchus; 66, bronchia; v, pulmonary vein, and a, artery; /, lobule. 
Fig. 42. The right eyeball, mesially and vertically divided, and posteriorly other orbital 
contents. Parts about natural size, and from the female Manatee. 
O.Rete, orbital vessels; m, muscles; on, optic nerve; don, infraorbital nerves; ca, ciliary 
artery; sc, sclerotic; cp, ciliary processes; /, lens. 
Fig. 43. A transverse section of the same eye behind the ciliary processes and iris. 
Fig. 44. A ventral view of the female body eviscerated and dissected, chiefly to show 
the long tendinous diaphragm and kidney thereupon, the intercostal vascular 
plexuses, and the lumbo-caudal muscles. 
