_Mustela africana_ 406 _Mustela africana africana_ Desmarest 409 _Mustela africana stolzmanni_ Taczanowski 413 Subgenus =Putorius= Cuvier (Black-footed Ferret--not treated in present work) _Mustela nigripes_ (Audubon and Bachman) Subgenus =Lutreola= Wagner (Minks--not treated in present work) _Mustela vison_ _Mustela vison vison_ Schreber _Mustela vison mink_ Peale and Beauvois _Mustela vison lutensis_ (Bangs) _Mustela vison evergladensis_ Hamilton _Mustela vison vulgivaga_ (Bangs) _Mustela vison letifera_ Hollister _Mustela vison lacustris_ (Preble) _Mustela vison energumenos_ (Bangs) _Mustela vison evagor_ Hall _Mustela vison aestuarina_ Grinnell _Mustela vison nesolestes_ (Heller) _Mustela vison melampelus_ (Elliot) _Mustela vison ingens_ (Osgood) _Mustela macrodon_ (Prentiss) ARTIFICIAL KEY TO AMERICAN SPECIES OF THE GENUS MUSTELA PAGE A Length of upper tooth-rows less than 20 mm. in males and 17.8 mm. in females. B Postglenoid length of skull more than 47 per cent of condylobasal length. C Tail without a black pencil and with at most a few black hairs at extreme tip; in both sexes mastoid breadth ordinarily exceeds breadth of braincase, _Mustela rixosa_, least weasel, p. 168 C' Tail with a black pencil; in females mastoid breadth ordinarily exceeded by breadth of braincase, _Mustela erminea_, ermine, p. 87 B' Postglenoid length of skull less than 47 per cent of condylobasal length. D Tail with distinct black tip; midventral line white, yellowish, orange, not same color as upper parts; p2 present; thenar pad on forefoot absent, _Mustela frenata_, long-tailed weasel, p. 193 D' Tail without black tip; midventral line same color as upper parts; p2 absent; thenar pad on forefoot present, _Mustela africana_, tropical weasel, p. 406 A' Length of upper tooth-rows more than 20 mm. in males and 17.8 mm. in females. E Abdomen all white; face with blackish mask; m1 lacking even a trace of a metaconid; distance between upper canines more than width of basioccipital as measured between foramina situated midway along medial sides of tympanic bullae, _Mustela nigripes_, black-footed ferret.