34 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q0\ 



tf— ■ + t>— °z + r"- 3 2 i -f &c. , , x wit— • — mB-" 1 — , . . . 



v .-> + v> z + v *-h>+zc. = ^ hen v = z ) - ;^^— T 73T' wh,ch 1S the 

 same as the expression (— — ) before derived, with only the sign of m changed. 

 The remainder of the process being the same as before, shows that the series is 

 general, or extends to all cases, regard being had to the signs, a. e. d. 



XVII. A Description of the Anatomy of the Sea Otter, from a Dissection made 

 Nov. 15, 1795. By E. Home, Esq., F. R. S., and Mr. Arch. Menzies. p. 385. 



The subjects from which the following description is taken, were procured from 

 the natives on the west coast of America, near Queen Charlotte's Isles, by Mr. A. 

 Menzies, surgeon in the navy, and naturalist to the expedition fitted out by go- 

 vernment for making discoveries, under the direction of Capt. Vancouver. The 

 sea otter is not confined to this particular situation; it was met with in the course 

 of the voyage every where along the coast, from 30° to 62° north lat., and some- 

 times even 100 leagues out at sea. Two sea otters were examined, both of them 

 males ; one was a cub not old enough to leave the mother, the other appeared to 

 be full grown. 



A description of the external appearances. — The large one measured 4 feet 4 

 inches from the nose to the extremity of the tail. The body appears a little com- 

 pressed, and is nearly of the same thickness throughout ; its circumference is 2 feet 

 A\ inches. The colour of this animal varies in different subjects, but in general 

 the head and neck are grey, or of a silver colour ; the back, sides, legs, and tail, 

 black and glossy ; in some, the longest hairs are tipped with white, which gives 

 them a beautiful greyish cast ; the breast and belly also vary from a silver grey, to 

 different shades of light brown. The long hairs shine with a brilliant gloss, but 

 the short fur is exceedingly fine, soft, and thick set ; and its colour is either a light 

 chesnut-brown, or it has a silver hue, and a beautiful silky gloss. In the cub 

 state, the hair is a long, coarse, shaggy fur, of a brown colour, destitute of any 

 gloss ; but as the animal grows up the fur becomes finer and more beautiful. 



There are 2 nipples, one on each side of the sheath of the penis, nearer to the 

 anus than to the external orifice of the sheath. The sheath of the penis does not 

 project beyond the skin of the neighbouring parts ; its external orifice is 7 inches 

 from the anus, but the sheath itself extends 14- inch further on under the skin of 

 the belly ; by which means the penis, when inclosed in it, has its point more effec- 

 tually defended from injury. The head is somewhat compressed, and small for the 

 size of the animal. The nose and upper lip are very muscular, and protrude about 

 1-J- inch beyond the gums and lower lip. The eyes are small, and placed directly 

 over the angles of the mouth, about -£- way between the ears and the tip of the 

 nose. The ears are nearly naked, black, slightly notched at the ends, and about 1 

 inch long ; they are 6 inches removed from the tip of the nose. The whiskers 

 are in great number, they are white and strong, they arise from the upper lip on 

 each side of the nose. There are a few weak long hairs on the eyebrows. 



