300 NORTH AMERICAN MUSTELID.E. 



to ear 3i to 4 iucbes; ea-r less than an inch bigb, and about' as 

 broad; fore foot from wrist 3| iiicbes; biud foot 4 incbes; girtb 

 of body about li feet; stature a foot or less; weigbt ordinarily 

 20 to 25 pounds. I have recognized no particular sexual dif- 

 ferences, tbougb the female may, as usual in this family, aver- 

 age smaller than tbe male. 



Comparison with allied species. (See plates XVI [, XVIII.) 



Tbe differences between the present species and L. vulgaris 

 of Europe are decided and unmistakable, in fact much stronger 

 than those usually subsisting in this intricate group, where 

 recognition of species is rendered difficult by similarity in form 

 and color. Some of the characters of L. vulgaris have been 

 already noted. It is a much smaller animal ; the nasal pad is 

 reduced to a small bald spot strictly confined betwixt the nos- 

 trils ; and there is no hair on the soles or palms. The cranial 

 characters are still stronger. A great many details of difi[er- 

 ence that might be adduced may be summed in the statement 

 that the skull of L. vulgaris is less massive, narrower for its 

 length, and with weaker dentition. The prominent peculiari- 

 ties are these : There are no decided postorbital processes 

 defining the orbit above. The postorbital constriction is 

 great, the skull being at this point less than one-fourth as 

 broad as it is across the mastoids, instead of nearly one-third 

 such measurement, as in L. cayiadensis. The zygomatic widtli 

 is contained one and four-fifth times in the total length, instead 

 of only about one and two-fifths, as in L. canadensis. The ros- 

 trum is decidedly more produced and narrower, and the nasal 

 bones are of a correspondingly different shape. The inner 

 spur of the posterior upper premolar in L. vulgaris is a semi- 

 circle, only about half as long as the tooth; in L. canaden- 

 sis, the same part of this tooth is developed along the whole 

 inner border of the main moiety. There are other minor den- 

 tal peculiarities. (Compare Plates XVII and XVIII.) 



A skull of the Mexican Otter above mentioned as entirely 

 distinct from L. canadensis^ and which is probably the species 

 named L. californiea by Gray (but certainly not the one so 

 called by Baird), is of the same general character as that of 

 L. canadensis, in fact presents no very strong points of differ- 

 ence. The inner part of the back upper premolar, however, is 

 rather triangular than quadrate, lacking the bulge of the pos- 

 terior part, conspicuous in L. canadensis, which causes the part 



