THE CHAWIJNd WATEU BEE'J'LES. 201 



they may often be noted crawling slowly over the partially decayed 

 aquatic plants, especially alga;. On account of their feeble swim- 

 ming powers they may be easily captured by raking the mass of 

 vegetable matter onto the bank, when the beetles, on crawling out 

 to regain the water, may be secured. The name of the family is 

 derived from the Greek and means "sailing the sea," or "covered 

 with water." 



The larvEe of the Haliplids live in the same places as the adults. 

 They are composed of slender segments, each, except the head, 

 being furnished on the back -with fleshy lobes, bearing spiny tips, 

 while the last segment is extended into a long tapering appendage. 



The principal paper, including descriptions of the North Ameri- 

 can species of this family, is by 



Crotch. — "Revision of the Dytiscidae of the United States," in 

 Trans. Amer. Ent. Soc.. TV. 1873, 3S3-.385. 



The North American species nre divided amon" three genera, 

 two of whieh are represented in Indiana. 



KEY TO INDIANA GENEKA OP HALIPLID^, 



(/. Terminal joint of palpi small, awl-shaped; intervals of elytra punctate; 

 thorax without black spots at base. I. HALiPLtiS. 



('('. Terminal joint of palpi conical, longer than the third; intervals of ely- 

 tra without punctures ; thorax with two small round impressed black 

 spots at base. II. CNEMinoTis. 



I. Haliplus Latr. 1806. (Gr., "the sea -f sail.") 



Of the ten species of this genus known from the United States, 

 six have been triken in Indiana, while another may occur. 



KEY TO INDIANA SPECIES OF HALIPLUS. 



(/. Thorax without a liusal impression. 



&. Prosternuni marj^'ined at sides; elytral punctures deeper at liiise tlian 

 apex. 

 <;. A distinct black spot on middle of front margin of thorax. 



383. TEioPsis. 

 r-c. Thorax without black spot, sometimes slightly darker at apex. 

 d. Elytra not sinuate near apex. 



c. Spots of elytra distinct ; size larger, 3.5-i mm. FAScrAxus. 



ce. Spots more or less confluent; size smaller, 2.."> mm. 



384. LEwisir. 

 (/'/. Elyti-a distinctly sinuate near apex; spots often slightly con- 

 nected but not confluent. :!S5. boreaeis. 

 /;/(. Prosternuiu flat, not mar.i^'ined n( sides; elytral jiunctui-es not deeper 

 at liase than ajiex; elytra dull brownish-yellow with eliingate lilack 



spots. 38C. CEIBABIUS. 



