DE. J. MUEIE ON THE EOEM AND STEUCTUEE OF THE MANATEE. 133 



That portion of the subcaudal surface which, as it were, defines the fleshy limits of 

 the tail possesses numerous short sinuous transverse wrinkles ; but the remainder of the 

 expanded organ is devoid of these. The upper surface is comparatively smooth. The 

 scaly epidermal patching met with on the fore part of the body is very sparsely distri- 

 buted on the tail — and where present is chiefly at the margins, as small punctate 

 dermal tracery. All round the very posterior edge of the caudal expansion, but on the 

 dorsal surface, there is a smooth cord-like rim one eighth of an inch broad. 



The thickness of the skin varies with its situation. Near the generative outlet I 

 found it to be 0-4 inch, the epidermis itself -^g- of an inch\ 



2. Hair and Bristles. — The sparsely distributed hairs upon the head, trunk, tail, and 

 extremities of Manatus and Halicore have been mentioned by all observers; I shall 

 but append a supplement to their remarks. Two kinds of dermal appendages have 

 been noted — longish pliant hairs, and short stiff bristles. The former, scattered over 

 the back and belly, have an average length of 1^ inch ; but many are shorter, though 

 a fair proportion reach and even exceed 2 inches. Each hair is very fine, soft, smooth, 

 and pale-coloured. Upon the limbs the hairs are considerably shorter than above 

 stated, but are closer set together, especially on the palmar aspect. On the upper 

 surface of the head they are likewise curtailed in length compared with those on the 

 body and tail. At each angle of the mouth, partially within the lips, developed on the 

 upper, but still more so on the lower jaw, is a pretty thick bunch of long, somewhat 

 coarse, hairs. Of these Stannius says that they cause the cheeks to appear thickly 

 beset with hair ; but this neither his nor Vrolik's sketches clearly exemplify. 



These hairs within the mouth are not without interest, as, it may be, they, and not the 

 horny palate, are the homologues of the whalebone or baleen plates of some Cetacea. 



Quite under the chin, as Vrolik shows, the hairs are stiffer than those described, 

 imiform in calibre, and about a quarter of an inch in length. These, both in outward 

 aspect and texture, are intermediate between the hairs of the body generally and the 

 true bristles. The latter are stout, blunt-pointed, and spring from the pits of the rough 

 muzzle and ridged lower lip. They vary in total length from 0-3 to 0-4 inch, though not 

 more than half that is free. Towards the nares, where smallest, they project only 

 slightly, but lower down increase in size and rigidity, so that when the hand is passed 

 over the surface it feels like a rasp. At the dependent angle on each side of the muzzle 

 is a circumscribed oval prominence, half an inch in diameter, where the ridges, furrows, 

 and bristles are specially pronounced. This spot would seem to possess most tactile 

 delicacy ; for twigs of the infraorbital and facial nen-es are abundant thereto. On the 

 semilunar, pale-coloured, tough, lower lip, there are three transverse rows of bristles 

 and trapezoidal ridges. Besides bristles there were many of the long silky hairs scat- 

 tered on the face of the muzzle, they being in greatest plenty, however, circumferentially. 



' For its microscopical composition, consult Professor Paulsen's obserrations, and woodcut in Brandt's Symb. 

 Siren, iii. p. 252, and Leydig's Lehrb. d. Histol. p. 87. 



