188 



U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



There is apparently a preponderance of the light tips to the long hairs along the middle of 

 the hack and on the sides of the tail. 



The concealed under fur is liver hrown at the tip; that on the helly and sides heing yellowish 

 white at the hase, the amount and clearness of the white decreasing to the median line of the 

 back. 



A comparison of this specimen with a very fine L. canadensis, killed in the Potomac river, 

 near Washington, presents the following differences : 



The naked muzzle is decidedly shorter antero-posteriorly, the width remaining the same. 

 Length of the naked portion is less than its width, instead of being greater, as in the L. 

 canadensis. The angle of the posterior outline is consequently less acute and is shorter, not 

 running so far back on the forehead. The septum of the nostrils is narrower, and there is no 

 naked point running down from its middle line and partly bisecting the middle of the upper 

 lip, as in L. canadensis. 



There is much less hair on the under surfaces of the feet. The peninsula of hair extending 

 forward over the naked portion of the sole in L. canadensis is wanting entirely, and there is 

 but little hair on the web between the fingers. The first, fourth, and fifth fingers are entirely 

 naked under their middle line, instead of having the balls isolated by hair from the naked palm. 

 A nearly similar condition prevails in the hind feet, except that there is no hair on the middle 

 line of the inferior surface of any of the toes. 



How far the characters thus adduced are sufficient to establish differences in species can only 

 be determined by a comparison of more specimens. All the eastern skins of otters I have seen 

 agree pretty well with the above description of L. canadensis, the hair on the under surface of 

 the feet being distinctly appreciable when the digits are approximated, which is not the case in 

 the California specimen. As a species has been instituted by Gray, I shall adopt it, whatever 

 hesitation I might feel at introducing a new name based on a single specimen. 



A comparison of the skull of the California otter with that of eastern specimens exhibits very 

 close affinities, both being distinguished from the European L. mdgaris by common character 

 istics of great development of post orbital process of frontal bone, broad interorbital space, very 

 broad and short muzzle, &c. 



List of specimens. 



