2l6 



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 



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IP 



Pig. 71.— American Manatee (Manatus americanus), from life. Proc. Zool. Soc. 1S81, p. 457. 



valve-like slits, at the apex of the muzzle. The eyes 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 



