THE PREDACEOUS DIVING BEETLES. 



(I. First and second ventral segments smooth or obsol'etely punctate; 

 elytra finely punctate. 406. affinis. 



dd. First and second ventral segments coarsely but sparsely punc- 

 tate ; elytra coarsely punctate. 407. fuscatus. 



403 (1270). Bidessus flavicollis Lee, Proc. Phil. Acad. Nat. Sci., 1855, 



295. 



Oblong-oval, opaque. Head, thorax, legs and under surface yellow; 

 elytra fuscous or brownish, each with two paler spots on the sides. Thorax 

 and elytra densely and finely punctate, the basal grooves of the former 

 very short. Hind coxae not longer than broad. Length 1.2-1.5 mm. 



A single specimen from Hudson Lake, Laporte County, July 15. 

 Probably occurs sparingly in the lakes of the northern third of the 

 State. Known from Illinois, Pennsylvania and New England. 



404 (1273). Bidessus pulicarius Aub6, Spec. Gen., VI, 1838, 494. 

 Oblong-oval, opaque. Head, thorax and legs reddish-yellow ; elytra 



dark brownish-yellow, a faint yellow submarginal spot behind the middle 

 and another near the apex ; postpectus and abdomen piceous. Elytra close- 

 ly punctulate and covered with fine hairs visible only beneath the lens. 

 Length 1.5-1.7 mm. 



Laporte, Kosciusko, Marshall and Marion counties; scarce. May 

 31- August 15. 



405 (1278). Bidessus lacustris Say, Trans. Anier. Phil. Soc, II, 1823. 



103; ibid. II, 516. 

 Oblong-oval, shining. Head and thorax dull reddish-yel- 

 low ; elytra brownish-yellow clouded with darker ; under 

 surface usually black. Elytra very finely and indistinctly 

 punctate. Length 1.4-1.8 mm. (Fig. 108.) 



Throughout the State ; frequent. April 15-Au- 

 gust 20. 



406 (1275). Bidessus affinis Say, Trans. Amer. Phil. 



Soc, II, 1823, 104; ibid. II, 517. 

 Oblong-oval, feebly shining. Head, thorax and legs red- 



rig. lUo. X Jo. 



dish-yellow; elytra and under side fuscous brown, the for- (Original.) 

 tner often with paler elongate markings. Length 1.5-1.8 mm. 



Throughout the State, frequent ; especially so in the northern 

 lakes. April 4- August 20. 



107 (1279). Bidessus fuscatus Crotch, Trans. Amer. Ent. Soc, IV, 1873. 

 391. 



Resembles affinis but darker and more shining. Known by the coarser 

 punctures of elytra and hind coxal plates and the shorter impressed stria 

 at base of elytra. Head and thorax almost smooth. Length 1.7-2 mm. 



Starke County; scarce. Collected by sweeping along the north 

 margin of Bass Lake. May 19. 



