STAPHYLINID.E 233 



as long as the two preceding; prothorax fully twice as wide as long, 

 the sides very moderately converging though strongly arcuate from base 

 to apex; elytra parallel, transverse, exactly equal in width to the pro- 

 thorax, the sides straight, the suture fully a fourth longer than the pro- 

 notum and much shorter than the elytral flanks; abdomen fully as wide 

 as the elytra, parallel, narrowing very slightly at apex, very much longer 

 than the anterior parts taken together. Length 0.85 mm.; width 0.26 

 mm. New York (near the city). 



This species is allied rather closely to pusillima but differs deci- 

 sively in its much more close-set punctures and vestiture of the 

 pronotum, in its less abbreviated elytra, in the very much stouter 

 antennal club and more transverse penultimate joints of the an- 

 tennae. 



Subfamily MYLL^NIN^. 



We have in this subfamily a closer approach to the Tachyporinae 

 than occurs anywhere within the limits of the Aleocharinae, not only 

 in the limuloid form of the body but in the type of sexual characters. 

 The body is almost invariably finely, very densely punctulate and 

 pubescent. The three genera of the Myllaeninse differ among them- 

 selves in tarsal structure even more profoundly than do the three 

 principal tribes of the Aleocharinae and each should form the type 

 of a distinct tribe. In Gymnusa, the only genus of the Gymnusini, 

 the tarsi are long and well developed, with the basal joint of the 

 posterior greatly elongated; in Deinopsis, however, they are very 

 short and slender, with the basal joint of the posterior not at all 

 elongated. 



Tribe GYMNUSINI. 



Gymnusa Grav. 



The body in Gymnusa is larger than in either Deinopsis or Myl- 

 Icena and the tarsi are 5-jointed throughout. The following species 

 or subspecies has been hitherto confounded with the European 



brevicollis: 



Gymnusa atra n. sp. Greatly resembles brevicollis Payk., but smaller 

 and sensibly narrower, similar in its deep black coloration, slender an- 

 tennae and rufous tarsi, the head relatively a little larger, the prothorax 

 slightly less transverse, with the rounded sides somewhat less converging 

 anteriorly; elytra and abdomen nearly similar; antennae of the male with 

 the joints rather less elongate, the female antennae also having the joints 

 shorter throughout but similarly though rather less strongly incrassate 

 distally. Length 3.6-4.0 mm.; width 1.3-1.38 mm. Massachusetts 

 (Cambridge) and Canada (Ottawa). 



