8 NORTH AMERICAX MUSTELID.E. 



Schedule of differcniial cluinicters of the Xorth Jmcrican genera — Coatinued. 



Antoorbital foramen bounded by atoiit process, presenting more or 



leas vertically 



Aperture of nares iu two planes, approaching the vertical and hori- 

 zontal 



one plane, or nearly so, more or less oblique. .. 

 Auditory bullae at maximum of inflation, with shortest and least 



tubular meatus 



much inflated, with moderate coustrictioii into 



the tubular meatus 



little inflated, much constricted across the meatus. 



Mastoids little developed, outward or backward 



more developod, outward 



much developed, downward 



Periotic region contracted, bringing paroccipitals close to auditory 



bulla) 



expanded, removing paroccipitals from buUie, and 



horizontal 



expanded, removing paroccipitals from buUas, very 



oblique '. . 



Glenoid fossa^ shallow, open, without anterior ledge, presenting more 

 forward than downward, never locking condyles. .. 

 moderately deep and close, with anterior ledge pre- 

 senting downward-forward, never locking con- 

 dyles 



very deep and close, with strong anterior and pos- 

 terior ledges, sometimes locking condyles 



Coronoid process of jaw in profile conical, erect, apex forward of 



condyle 



obtusely falcate, sloping, apex 



overhanging condyle 



Lower border of jaw straightish from symphysis to posterior angle, 

 usually ascending posteriorly, in 



straight or concave line 



Toes scarcely or not webbed, with ordinary ratio of lengths 



fully webbed, with ordinary ratio of lengths 



those of the liind feet elongated, with extraordi- 

 nary ratio of lengths 



Fore claws long, stout, little curved, highly foasorial 



moderate or short, curved and acute, not fossorial 



Body very stout; size very large; tail bushy, short; appearance 



somewhat bear-like 



rather slender or extremely so ; size medium and small ; tail 



long, terete , 



stout; size medium and small; tail long, very bushy , 



stout, much depressed; size medium ; tail short, distichous — 

 etout, cylindrical ; size large; tail long, conical, close-haired.., 



Habits chiefly terrestrial 



terrestrial and highly arboreal 



strictly terrestrial and more or loss fossorial 



aquatic (fluviatile, lacustrine, or maritime) 



aquatic (marine) 



MustelidfB. 





-1 w 



Sucli a table as this might be indefinitely continued, but the 

 foregoing analysis of leading ditferential characters suffices for 

 preseut purposes. 



