CRANIAL VARIATION IN LUTRA CANDENSIS. 307 



a par with each other ; the eiicls of all are obtusely rounded, 

 without obvious lobatiou. 



The back lower inohir is siiuiU and circuhir, as usual ; it shows 

 no special points. The front lower molar consists of an anterior 

 tricuspidate half and posterior dei)ressed portion. The three 

 cusps are very prominent, subequal in size, forming a triangle, 

 with one angle anterior and median, the two others posterior 

 and lateral ; the postero-internal cusp is rather sjnaller than the 

 two others, the ridge connecting which forms the trenchant 

 edge of the tooth. The back part of the tooth is a simple de- 

 pression, with raised periphery, which, at its outer part, is twice 

 nicked, with slight marginal cusps as a consequence. The pos- 

 terior premolar is a stout conical cusp, well heeled fore and 

 aft, with a secondary cusp half-way up its back border, as in 

 Taxidea. The next premolar is smaller, but similar, except in 

 lacking the secondary cusp. The front premolar is again simi- 

 lar, but smaller still, and without an anterior heel, being closely 

 apposed to the canine. The latter is short, very stout, ^Ind 

 much curved. The inferior incisors are much crowded and very 

 irregular, even more so than in Mmtelinm^ offering an interesting 

 approach to the condition which culminates in Enliydris in the 

 disappearance of one pair. The outer pair are moderatelj^ larger 

 than the rest ; the next pair — the middle tooth on each side — 

 set almost entirely back of the general incisor plane ; they are 

 quite deep, though little of their face appears in front. The 

 middle pair are narrow, and closely approximated. The ends 

 of the outer pair are lobate ; of the others, not appreciably so. 



Variations in the skull of tlie Otter. 



As in other cases, I present under this head Mr. J. A. Allen's 

 measurements and comments, extracted from the paper above 

 cited in the synonymy : — 



" Specimens of this species from northern and southern locali- 

 ties do not differ materially in size ; skulls from Xewfoundland, 

 Maine, Lake Superior, Washington, and Georgia agreeing very 

 closely in dimensions. In a series of eighteen (mainly from 

 northern localities), nine attain or exceed a length of 4.U5, and 

 three reach 4.50, while two only fall as low as 4.00. Seven speci- 

 mens from the vicinity of Lake Umbagog, Maine, (in Mus. 

 Comx). Zool.) average 4.28 in length and 2.93 in width j two of 

 these reach 4.50 in length and two fall slightly below 4.00 (3.96 

 and 3.97). Two specimens from AVashington, D. C, have a 



