154 PROCEEDINGS OF THE ACADEMY OF [1894. 



tween the first and third, seen in all other species of the Muselklcz. 

 There is no symphysis between lower canines and first premolars, the 

 latter over-lying the former mpoilnxnke and the second lower molar 

 is relatively as large as in the upper series. Viewed laterally, the 

 mandibles of peninsvlce describe a nearly perfect half ring due to the 

 great outer convexity of the ramus, its rounded, compressed angle 

 and abrupt upward anterior curve. The ramus is also very thick 

 (laterally) for its width (perpendicularly), the former dimension at 

 the base of second molar is greater than that of largest /re»«i(/-s while 

 the latter dimension is one-third less. In pe)i!nsul(e the width (hori- 

 zontal) of the articular process of mandible is relatively much less 

 than we find it in Jrenatm and xanihogenyx, in this approaching er- 

 minea, but it is, as in other parts, relatively stouter than in any of 

 them. 



Measurements^ (from stuffed skin) :— Total length, 375 ; tail verte- 

 brae (vertebrte remaining in skin), 100; hind foot, 40; pencil, 16. 



Skull — Posterior base of incisors to post-palatal notch, 18.7; length 

 of nasals, 9; interorbital constriction, 10.7; articular process of man- 

 dible to anterior base of incisor, 26 ; height of coronoid process from 

 angle, 12. 



My examination of the skulls of the above mentioned species 

 makes it apparent, not only that the Florida animal is distinct from 

 its allies in the United States, but that xanthogenys should be classed 

 as a good species, separable from frenatus not only in external but 

 in cranial characters. The relationships between frenatus and bra- 

 siliensi>;, of which some authors make it a sub-species, I am unable 

 to discuss, from lack of material. Xanthogevys, in addition to its 

 constant and well known color differences, may be cranially separated 

 i'rom frenatus of same age by the decidedly and constantly smaller 

 size, the relative shallowness and flatness, the greater relative width 

 to length and the sudden constriction of the skull behind the supra- 

 orbital processes. The pterygoid fossa is also relatively shorter and 

 both absolutely and relatively wider than in frenatus. The length of 

 largest freiiatus skulls is 54, while that of the largest xanthogenys 

 is 46. 



A stufl^ed specimen of this new weasel was sent by JNIr. Dickinson in 

 February, 1894. So far as can be determined, this is the first instance 



1 All measurements iu millimeters. 



