Casey — A Revision of the American Paederini. 143 



Lathrobioma of the non-plicate series. It is probable that 

 both of the known species are found with ants, at least at 

 certain seasons, for a specimen of pallidida, given me by the 

 late Mr. Julich, was said to have been taken by him in an 

 ant's nest. The degree of intimacy between various beetles 

 and ants of course varies greatly, and, in many Staphylinids, 

 such as those under discussion, there is but little evidence of 

 true symbiosis, or it may be said at least, that the degree of 

 association has not been carried sufficiently far to have mod- 

 ified their structure to any noticeable extent. The eyes, it 

 is true, are unusually small, but they are perfectly formed and 

 probably perform the full function of eyes as in other genera. 

 The two species in my cabinet may be briefly described as 

 follows : — 



Form slender, parallel, pale testaceous throughout, polished; head as long 

 as wide, very slightly enlarged toward base, the sides broadly arcuate ; 

 angles broadly rounded, the punctures not very coarse, sparse; eyes at 

 fully three times their own length from the base; antennae rather thick, 

 slightly longer than the head and prothorax, gradually and distinctly 

 incrassate, the medial joints less than one-half longer than wide; pro- 

 thorax somewhat narrower than the head, longer than wide, the sides 

 very feebly converging from the distinct apical angles, sometimes 

 broadly and feebly sinuate anteriorly, the basal angles rounded, the 

 punctures fine, very sparse and feeble, sparsely subserial along the 

 median smooth area; elytra slightly shorter than wide in the male and 

 but little longer in the female, distinctly shorter than the prothorax in 

 both sexes and obviously wider, the sides straight and strongly diverg- 

 ing, the punctures very fine, sparse and feeble, obscurely subserial in 

 arrangement; abdomen at base as wide as the elytra or nearly so, dis- 

 tinctly wider posteriorly, finely, not densely punctulate and somewhat 

 shining. Male with the fifth ventral wholly unmodified, the sixth 

 broadly obtuse at tip, with a small simple subtriangular and gradually 

 formed emargination, three times as wide as deep and a third as wide 

 as the apex, the lobes of the latter broadly, feebly rounded; female with 

 the sixth ventral evenly and strongly rounded at tip. Length 4.1 mm. ; 

 width 0.68 mm. Massachusetts (Lowell) and New York (Staten 

 Island pallidnla Lee. 



Form still more slender, with smaller head and prothorax and much 

 larger elytra; coloration and lustre similar; head fully as long as wide, 

 rather finely, moderately sparsely punctate, broadening slightly toward 

 base, the sides broadly arcuate, the angles widely rounded; eyes at 

 three times their length from the base ; antennae extending to basal 

 third of the elytra, nearly as in pallidula; prothorax elongate, equal in 

 width to the head, parallel, the sides very feebly arcuate; anterior angles 

 distinct, the posterior narrowly rounded; punctures fine, feeble and 



