Casey — A Revision of the American Paederini. 143 
Lathrobioma of the non-plicate series. Itis probable that 
both of the known species are found with ants, at least at 
certain seasons, for a specimen of pallidula, given me by the 
late Mr. Jiilich, 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 fromthe 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 ang 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 
Tsland..cesceccccccsccesces cecesccnscrecccccesese cesses Pallidula Lec, 
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 
