THE LONG-TOED WATER BEETLES. 



677 



KEY TO SUBFAMILIES OF PARXID.E. 



a. Abdomen with more than five ventral segments; front coxse with very 

 large trochantin ; body subdepressed. 



Subfamily I. Psephenin^:, p. 677. 

 aa. Abdomen with only five ventral segments; body convex. 



ft. Front coxse transverse, with distinct trochantin; body clothed with 

 a dense silky pubescence. Subfamily II. Parxix.e, p. 678. 



hb. Front coxa? rounded without trochantin ; body feebly pubescent. 



Subfamily III. Elmix.e. p. 679. 



Subfamily I. PSEPHENINAE. 



In this subfamily the head is free, not retractile ; labium broad, 

 entirely covering the mandibles; maxillary palpi elongate, the last 

 joint wide, hatchet-shaped; antenna? widely separated, serrate, 11- 

 jointed. longer than head and thorax; prosternum carinate. pro- 

 longed behind into an acute point which fits into a narrow groove 

 extending the full length of the mesosternum ; abdomen of male with 

 seven ventral segments, the first and second united, fifth broadly 

 emarginate. sixth deeply bilobed. visible only around the notch of 

 the fifth; seventh rounded, entire, filling the notch of the sixth; 

 female with the segment corresponding to the sixth in male absent. 

 The subfamily is represented by the single genus 



I. Psephenus Hald. 1863. (Gr.. "dark or obscure.") 



Four species represent the genus in the United States, one of 

 which occurs in Indiana. 



1295 (3914). Psephexus lecoxtei Lee. Proc. Phil. Acad. Nat. Sci.. VI.. 

 1S52. 41. 



Oval, subdepressed. narrowed in front, obtusely 

 rounded behind, very finely punctate and pubescent. 

 Black or dull brownish-black ; head and thorax usually 

 darker, always deep black in the female. Base of 

 thorax twice as wide as apex, bisinuate, distinctly 

 lobed at middle ; hind angles acute, sides regularly 

 curved. Length 4.5-6 mm. (Fig. 252.) 



Hudson Lake, Laporte County and pool near 

 Delong. Fulton County; scarce. August 20. 

 Probably occurs throughout the lake region of 

 the northern third of the State. LeConte says that "the perfect 

 insect lives on bushes oi^er the surface of running water and is also 

 found creeping over wet stones in the torrents. ' ' 



