264 FAMILY VI. HYDROPHILID^. 



XVI. CRENIPHILUS Mots. 1845. (Gr., "notch or bay + loving.") 



Very small, convex elliptical or oblong beetles, having the punc- 

 tures of elytra confused, thorax without a basal marginal line, and 

 also without the rows of large coarse punctures usually seen in the 

 species of Hydrobius. They usually occur in numbers amongst the 

 decaying aquatic plants along the margins of pools and lakes. 

 Three species have been taken in Indiana, while two others should 

 occur. 



KEY TO INDIANA SPECIES OF I'RENIPHILUS. 



a. Form oblong, fully twice as long as wide; tarsi slender, the hind pair 



fully as long as the tibiae; elytra distinctly narrowed almost from 



humeri to tips ; color piceous, shining, the side margins of both thorax 



and elytra pale. SUTURALIS. 



aa. Form broadly oval, not much longer -than wide, very convex; tarsi 



stouter, the hind pair shorter than the tibiae. 

 b. Prosternum distinctly cariuate. 



c. Elytra distinctly punctate; antennae eight-jointed. 



514. SUHCUPREUS. 



cc. Elytra very indistinctly punctate; antennae nine-jointed. 



515. DESPECTUS. 

 &&. Pros termini absolutely simple. 



(I. Black with a bronzed tinge; surface distinctly punctured; hind 

 femora strigose lengthwise and sparsely punctate. DIGESTUS. 



eld. Dull piceous without tinge of bronze; surface indistinctly punc- 

 tate; hind femora densely punctulate and pubescent. 



516. INFUSCATUS. 



C. suturalis Lee., length 1.5-2 mm., and C. digestus Lee., 2.5- 

 3.5 mm. in length, are both said to occur from Canada southward 

 to Georgia and New Mexico. 



514 (1657). CRENIPHILUS SUBCUPREUS Say, Jourii. Phil. Acad. Nat. Sci., V, 



1S25, 189; ibid. II, 293. 



Elliptical, convex. Above piceous. distinctly bronzed, the margins of 

 elytra often paler toward apex; beneath dark reddish-piceous, the tarsi 

 paler. Thorax and elytra equally, not closely punctate. Length 1.5-2 mm. 



Common along the margins of lakes in the northern part of the 

 State ; less so in the southern counties. April 23-August 26. 



515 (1658). CRENIPHILUS DESPECTUS Lee., New Sp. N. Arner. Col., 1863, 25. 

 Closely resembles subcupreus, but smaller and transversely more con- 

 vex. Surface more distinctly brassy, alutaceous with minute punctures, 

 sparsely placed. Length 3.5 mm. 



Marshall and Putnam counties ; scarce. April 17-October 17. 



516 (1655). CRENIPHILUS INFUSCATUS Mots., Bull. Mosc., Ill, 1857, 177. 

 Oval, very convex. Piceous or dark fuscous, the margins of thorax 



and elytra paler. Antennae nine-jointed, the club darker. Thorax very 



