Casey — A Revision of the American Paederini. 59 



wholly out of place in the European catalogues, — and the 

 Lithochares connect it with the Medones, although there is 

 evidently a closer relationship between the last two named 

 than between the Paederi and Lithochares, as shown by gen- 

 eral habitus. Our species will form three closely allied 

 genera. The four genera represented before me may be dis- 

 tinguished as follows : — 



Head large, more or less quadrate and broadly truncate at base; prothorax 

 very broad and strongly rounded at the sides anteriorly, strongly nar- 

 rowed thence to the base; integuments coarsely and sparsely punctate 

 and pubescent; fourth tarsal joint strongly bilobed; gular sutures dis- 

 tinct, moderately separated and impressed. General in distribution. 

 [= Paederomorphus Gaut.] Paederus 



Head relatively small, strongly narrowed behind the eyes and narrowly 

 truncate or rounded at base, the prothorax relatively much smaller and 

 more evenly oval 2 



2 — Punctures and pubescence coarse and sparse, the abdomen always very 



sparsely punctulate, with the dorsal segments more or less feebly, trans- 

 versely impressed at base; gular sutures gradually converging and 

 most narrowly — though somewhat widely — separated behind the 

 middle of the post-oral surface, always very feeble and unimpressed and 



sometimes subobliterated 3 



Punctures and pubescence finer and close-set, the abdominal segments 

 strongly, transversely impressed at base, first abdominal segment 

 without basal carina * 



3 _ Eyes moderate in size; abdomen obtuse; fourth tarsal joint rather 



wide and strongly bilolsed ; head and last two ventrals always black, 

 the elytra invariably dark steel-blue in color. Entire United 

 States Paederillns 



Eyes large; abdomen gradually narrowed toward tip; fourth tarsal joint 

 very narrowly bilobed ; color testaceous nearly throughout. Sonoran 

 regions Leucopaederus 



4 — Eyes moderate in size; fourth tarsal joint not wider than the preceding, 

 small and slightly bilobed; gular sutures becoming almost completely 

 confluent posteriorly. Europe *Paederidus 



The beetles of the present group are more highly and con- 

 spicuously colored than any others of the tribe, and, being at 

 the same time of moderately large size, especially in the 

 tropics, they have received considerable attention from sys- 

 tematic writers. Excepting the warmer parts of the new 

 world, our representatives are less numerous and less diver- 

 sified than those of Europe — an exceptional case in the 

 Paederini. 



