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 

 twice as long as wide 2 



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- 

 thorax 3 



Gular sutures almost straight, diverging only very near the base; head 

 almost as wide as the prothorax 4 



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 unmodified, the sixth narrow, broadly rounded at tip, with a 

 simple rounded sinus about a third as wide as the apex and between 



