Casey — A Revision of the American. Paederini. 93 
Litolathra n. gen. 
This genus, while closely allied to Lathrobium, differs in 
the arcuate form of the gular sutures, which are always widely 
separated and more remotely so at base than at the middle of 
the post-oral part of the head. The species are moderately 
numerous and are much smaller in average size than those of 
Lathrobium ; they also have a type of male secondary sexual 
characters — uniform throughout —differing from anything 
known in that genus. In addition, the antennae are longer, 
thinner and more filiform, and the abdomen is rather more 
tapering toward tip and always very densely punctulate and 
dull, —characters which also distinguish them from Lathro- 
bium. The general build of the body in species of the con- 
color type, suggests more rapid motion in running than in those 
of the confusa type, or in Lathrobium or Lathrobioma, these 
being relatively slow in their movements. The species repre- 
sented by material in my cabinet may be distinguished by 
the following characters: — 
Form elongate, fusoid, the elytra always much longer as well as wider than 
the prothorax, the legs rather slender; antennae not longer than the 
head and prothorax, moderately slender, the medial joints less than 
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Form subparallel, the elytra subequal in length to the prothorax or 
shorter; legs stouter, sometimes very stout in the male.............. 5 
2— Gular sutures distinctly arcuate, gradually diverging posteriorly from 
near the middle; head smaller, distinctly narrower than the pro- 
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Gular sutures almost straight, diverging only very near the base; head 
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3— Color black throughout, the legs and antennae rufous, polished, the 
abdomen dull; form very slender, the punctures of the head and elytra 
small, sparse, of the pronotum only moderately coarse and very sparse; 
head parallel, the basal angles very broadly rounded, beginning at one 
length of the eye behind the latter; neck fully half as wide as the head; 
prothorax distinctly elongate, about a fifth longer than wide, the sides 
parallel, arcuate anteriorly and posteriorly, the angles rather distinct; 
elytra distinctly longer than wide, parallel, almost a third wider than 
the prothorax and distinctly longer in both sexes; abdomen slightly 
narrower than the elytra, tapering behind. Male with the fifth ventral 
wholly unmodifled, the sixth narrow, broadly rounded at tip, with a 
simple rounded sinus about a third as wide as the apex and between 
