178 Trans. Acad. Sci. of St. Louis. 



sixth having a large, evenly and almost semicircularly rounded 

 sinus, occupying virtually the entire apex and between two 

 and three times as wide as deep, with its contour unmodified. 



Tetramedon n. gen. 



The labrum in this genus is remarkably similar to that of 

 Polymedon, but in every other respect the two genera are 

 altogether unlike, besides inhabiting quite different faunal 

 provinces. The gular sutures in Tetramedon are moderately 

 separated anteriorly, converging gradually to the base of the 

 head, where they are very narrowly separated and are well 

 impressed throughout. The single species known thus far is 

 the following : — 



Rather stout, parallel, somewhat depressed, moderately shining, black or 

 piceous-black, the elytra bright rufous, except a large basal cloud near 

 the scutellum, which is piceous, the legs and antennae pale red- brown; 

 head well developed, wider than long, the sides parallel and broadly 

 arcuate, the angles broadly rounded, the punctures not very coarse but 

 deep and very close-set, mingled with larger circular punctures bearing 

 stiffer setae; eyes at somewhat more than twice their own length from 

 the base; antennae rather long and thick, subequal in length to the head 

 and prothorax together; prothorax oblong, as long as wide, less than 

 four-fifths as wide as the head and punctured like the latter but more 

 finely and feebly, the sides straight and subparallel or just visibly con- 

 vergent from apex to base, the angles obtuse and distinctly, though not 

 very broadly rounded; elytra large, parallel, with slightly arcuate sides 

 and well marked basal angles, which are widely exposed at base, dis- 

 tinctly longer than wide, slightly wider than the head, two-fifths wider 

 and about one-half longer than the prothorax, moderately strongly and 

 closely punctured; abdomen about as wide as the head, parallel, the 

 sides just visibly arcuate, densely punctulate. Length 4.0 mm.; width 

 0.8 mm. New York (Hudson Valley) rufipenne n. sp. 



The unique type of this interesting species is a female, but 

 the male secondary characters are probably of the usual sim- 

 ple form. 



Platymedon Csy. 



This genus was proposed by the writer some years ago to 

 include a peculiar myrmecophilous Paederid of moderate size, 

 somewhat depressed and of broadly parallel form, with char- 



