382 CAENIVORA 



m ^1 = 34 ; upper carnassial as in Maries, its posterior (;usp low 

 but well developed, the height of its main cusp about half outer 

 border of crown ; upper molar between pyriform and pandurate in 

 outline, the constriction evident though not deep, the main axis of 

 the crown nearly perpendicular to sagittal line ; lower carnassial 

 without metaconid, the posterior lieel crossed by a longitudinal 

 trenchant ridge ; other teeth essentially as in Maries ; external 

 form slender, the muzzle obtuse, the ears low and rounded, the 

 legs short, the tail variable in length and in quality of hair, but 

 never so bushy as in Martes. 



Bemarks. — The genus Mustela, the most widely distributed of 

 the strictly terrestrial Mustelinse, is also the richest in species. 

 These fall into three main groups, extreme members of which 

 might be regarded as generically distinct. The existence of 

 species with intermediate characters makes it impossible to 

 define these groups by anything more than their average 

 differences.* They are therefore here treated as sub-genera. All 

 three are represented in Europe. 



KEY TO THE EUROPEAN FORMS OP MUSTELA. 



Brain-case broad, the mastoid width decidedly 

 greater than distance between basion and 

 palation ; auditory bullae triangular in outline 



(Sub-genus Pntorius, Polecats) M. putorms, p. 419. 



Underfur usually buffy grey (Central Europe) M. p. putoHus^ p. 423. 



Underfur usually yellowish (Southern Spain) il.p- aureolus^ p. 425. 



Brain-case narrow, the mastoid width less than 

 or about equal to distance between basion and 

 palation ; auditory buUfe not triangular in 

 outline. 

 Rostrum flattened above; inner margins of 

 auditory bulte strongly divergent pos- 

 teriorly ; tail bushy ; habits semi-aquatic 



(Sub-genus Lutreola, 'Minkii) M. lutnola, p. 415. 



Rostrum convex above; inner margins of auditory 

 bullffi nearly parallel ; tail not bushy ; habits 

 terrestrial (Sub-genus J\lustda, Stoats and 

 Weasels). 

 Tail with conspicuous black terminal area in- 

 cluding more than pencil ; skull with ros- 

 trum usually not so wide as interorbital 

 region; condylobasal length of skull never 

 less than 43 -4 mm. in adult male, or than 

 35 '4 mm. in adult female; hind foot 

 usually more than 43 mm. in males and 

 34 mm. in females (Stoats). 

 Brown of sides noticeably encroaching on 

 yellowish or whitish of underparts, the 

 line of demarcation irregular ; upper lip 

 always brown M. Jiibcniica, ]). 398. 



* At least so far as Lidrcola and true Mustela are concerned. Putorms 

 appears to be sharply circumscribed, so that it might readily be regarded 

 as a distinct genus (see remarks on p. 419). 



