216 SIRENIA 
there is no trustworthy evidence of its attaining a greater length 
than 8 feet. Its general external form may be seen in Fig. 71, 
taken from a living example in the Brighton Aquarium. The 
body is somewhat fish-like, but depressed and ending posteriorly in 
a broad, flat, shovel-like, horizontal tail, with rounded edges. The 
head is of moderate size, oblong, with a blunt, truncated muzzle, 
and divided from the body by a very slight constriction or neck. 
The fore limbs are flattened oval paddles, placed rather low on the 
sides of the body, and showing externally no signs of division into 
fingers, but with a tolerably free motion at the shoulder, elbow, 
and wrist joints, and with three diminutive flat nails near their 
extremities. No traces of hind limbs are discernible either exter- 
nally or internally ; and there is no dorsal fin. The mouth is very 
peculiar, the tumid upper lip being cleft in the middle line into two 
lobes, each of which is separately movable, as will be described in 
speaking of its manner of feeding. The nostrils are two semilunar 
Fic, 71.—American Manatee (Manatus americanus), from life. Proc. Zool. Soc. 1581, p. 457. 
valve-like slits, at the apex of the muzzle. The eves are very 
minute, placed at the sides of the head, and with a nearly circular 
aperture with wrinkled margins. The external ear is a minute 
orifice situated behind the eye, without any trace of pinna. The 
skin generally is of a dark grayish colour, not smooth and glistening 
like that of the Cetacea, but finely wrinkled. At a little distance 
it appears naked, but a close inspection, at all events in young 
animals, shows a scanty covering of very delicate hairs, and both 
upper and under lips are well supplied with short stiff bristles. 
The general form of the skull is seen in Fig. 72. The cerebral 
cavity is rather small as compared with the size of the animal 
and of oblong form; its roof is formed of the parietal bones as 
in ordinary mammals. The squamosal has an extremely large 
and massive zygomatic process, which joins the largely developed 
jugal bone in front. The orbit is small, but prominent and 
nearly surrounded by bone. The anterior nares taken together 
form a lozenge-shaped aperture, which looks upwards and extends 
