THE WATEE SCAVENGEE BEETLES. 263 



KEY TO INDIANA SPECIES OF HYDROBIUS. 



. Alternate intervals of elytra, 3-5-7-9, each with a row of coarse punc- 

 tures ; elytra black or piceous. 



ft. Elytra with well marked striae; form oblong. 511. FUSCIPES. 



6&. Elytra with rows of fine punctures; form short and very convex. 

 c. Hind femora merely closely punctate near base, not pubescent. 



512. TUMIDUS. 



cc. Hind femora densely punctulate and pubescent near base and along 

 the upper border. 513. GLOBOSUS. 



aa. Alternate intervals of elytra without rows of coarse punctures; elytral 

 stria? deep, the scutellar well marked ; elytra pale brown with scat- 

 tered small dark spaces. TESSELLATUS. 



511 (1653). HYDROBIUS FUSCIPES Linn., See Muls. Col. France, Palpic, 122. 

 Oblong-convex. Above piceous-black, shining; beneath black, the tarsi 



paler. Thorax finely and closely punctate. Elytra striate the two inner 

 and scutellar striae indistinct at base; striae closely punctate; intervals fiat, 

 not densely puuctulate. Length 6.5-8 mm. 



Lake, Starke and Kosciusko counties; frequent beneath rubbish 

 along the beaches of lakes. April 23-August 20. Probably occurs 

 throughout the State. Resembles Helocombus Irifidus, but more 

 convex and with shorter maxillary palpi, the last joint longer than 

 the preceding. 



512 (1648). HYDROBIUS TUMIDUS Lee.. Proc. Phil. Acad. Nat. Sci., VII. 



1855, 372. 



Oval, very little longer than wide, very convex. Piceous-black, shining, 

 slightly bronzed ; beneath black, legs piceous, tarsi paler. Thorax rather 

 closely and equally punctate and with coarser punctures in semicircular 

 row on sides. Elytra with ten rows of punctures, the first and second rows 

 not complete; intervals fiat, more coarsely punctured than in globosus. 

 Length 8-8.5 mm. 



Kosciusko and Marion counties; scarce. April 3-October 22. 



513 (1652). HYDROBIUS GLOBOSUS Say, Long's Exped., II, 1824, 276; ibid. I, 



182. 



Shorter, broader, more hemispherical than tumulus, 

 which it closely resembles. Surface similarly punctured, 

 but in each part more finely ; dorsal rows of punctures 

 more distinct. Hind femora with basal third opaque, 

 punctured and slightly pubescent. Scutellar stria dis- 

 tinct. Length 7.5 mm. (Fig. 129.) 



So far taken in Indiana only in swift water at 

 mouth of Donaldson's Cave, near Mitchell, Law- 

 rence County; scarce. Should occur throughout the State. May 

 5-September 11. 



H. tessellatus Zieg., 7-7.5 mm. in length, is said to occur from 

 Canada to Illinois and southward, but rare in every locality. 



