62 Trans. Acad. iSci. of St. Louis. 



Paederillus n. gen. 



This genus is much more boreal in range than Paederus 

 and almost entirely replaces the latter in the United States, 

 where it is distributed throughout from the Atlantic to the 

 Pacific. Its species are much smaller as a rule than those of 

 Paederus, and of more slender form, with little or no sexual 

 difference in the head; the elytra are, however, frequently 

 distinctly shorter in the male. The species are rather nu- 

 merous but closely allied among themselves, having a remark- 

 able persistency and uniformity of facies throughout. The 

 coloration of the body is constant, being as stated in the table 

 of genera, and the lustre is always shining, so that these 

 characters will not be mentioned in describing the various 

 forms below. The labrum is short and transversely truncate 

 throughout and completely edentate, with a small abrupt sub- 

 parabolic median sinus, devoid of medial denticle. The 

 species are usually gregarious and therefore plentiful in in- 

 dividuals when discovered ; those represented by material in 

 my cabinet may be described as follows : — 



Elytra large, much wider and longer then the prothorax in both sexes. .. 2 



Elytra shorter, never very much longer than the prothorax, even in the 

 female, and occasionally much shorter except in texanus 3 



2— Body slender, the legs pale throughout, the antennae blackish, pale 

 toward base and slightly paler at the immediate apex; head elongate - 

 oval, the eyes rather small but convex and prominent and at one-half 

 more thaa their own length from the base ; sides behind them rapidly con- 

 verging, evenly, feebly and circularly rounded throughout to the neck, 

 the angles obtuse and scarcely rounded, the base narrowly truncate; 

 prothorax like the head subimpunctate as usual, elongate-oval, widest 

 only slightly before the middle, narrower than the head; elytra very 

 long, parallel, a third wider and more than a fourth longer than the 

 prothorax in the male and distinctly wider than the head, the punc- 

 tures only moderately coarse and unusually sparse ; abdomen narrower 

 than the elytra, parallel. Male with the fifth ventral very feebly sinuato- 

 truncate at apex, the slit of the sixth narrow, parallel and very deep, 

 the sides straight, the bottom of the slit concealed from view in speci- 

 mens at hand; female not observed. Length 5.6 mm.; width 0.9 mm. 

 Florida floridanus Aust. 



Body slender and nearly similar to the preceding throughout, except that the 

 head is less elongate, the eyes a little larger, the sides behind them only 

 feebly convergent and straight to the basal angles, which are rather 



