332 NORTH AMERICAN MUSTELID^. 



meet the extremity of the nasals. More than a third of the in- 

 cisive foramen is maxillary, not intermaxillary. The orbito- 

 spheuoid recedes deeply in its surroundings. Other points will 

 appear in a topographical account of the skull. 



Viewed from above, the cranium differs from that of Lutra in 

 greater inflation of the cerebral walls, especially anteriorly, 

 where the encroachment upon the temporal fossic is decided. 

 Supraorbital processes are not so well developed (about as in 

 a Badger or Marten; the development in Lutra is exceptional). 

 The nasal orifice is greatly foreshortened in this view, owing 

 to the abrupt truncation of the mandible. It is difficult to say 

 how long the rostrum is, owing to the configuration of the parts, 

 but it may be estimated at about one-sixth of the total length 

 of the skull. Owing to its verticality, the anteorbital foramen 

 is scarcely seen in this view (it comes into sight inside the orbit 

 in Lutra). In old specimens, there is a strong sagittal crest 

 wanting in Lutra; in young ones, an irregular elevated tablet. 

 The top of the rostrum and adjoining interorbital space is a 

 smooth, flat tablet, as in Lutra. The occipital contour is much 

 as described in Lutra. 



In profile, the skull shows the same flatness on top as is seen 

 in Lutra^ with the additional feature of an almost vertical an- 

 terior truncation from the ends of the nasals, at little more than 

 a right angle, and almost straight down to the incisors. Such 

 contour is highly characteristic, and reminds one of the same 

 part in a Walrus. Owing to the slight supraorbital process and 

 little marked malar protuberance, the orbit is not well defined; 

 not so well as it is in the other subfamilies, excepting MepMtiuce. 

 The zygomatic arch rises abruptly behind. Its upper border 

 is then about straight and horizontal to the orbit ; its lower 

 border is a strong regular curve throughout. Other matters to 

 be noted in the profile view are much as in Lutra. 



From below: The zygomatic width is about three-fourths the 

 length; the intermastoid diameter but slightly less. The palate 

 reaches back of the molars about half-way to the ends of the 

 pterygoids. The emargination between these bones is extremely 

 wide and shallow. Perhaps here only in the family, the depth 

 of the emargination is no greater, or less than, its width. The 

 recess is sometimes almost semicircular, though the sides are 

 usually more nearly parallel, and the end transverse. In detail, 

 the shelf of the palate is altogether irregular. The walls of the 

 glenoid fossa3 are rarely, if ever, so much developed as to lock 



