238 



FAMILY V. GYRINIDiE. 



oa. Last ventral elongate, conical; labrurn prominent; scutellum invisible; 

 length 6 mm. Gybetes. 



I. Gyrinus Linn. 1733. (Gr., "a circle or ring.") 



Our members of this genus are smaller, more 

 narrow and more convex than those of the next. 

 They have eleven rows of distinct punctures on 

 each elytron which, when held in a certain light, 

 usually reflect a golden tint; the legs are always 

 recldish-brown or yellowish in hue. (Fig. 121.) 

 On account of the close resemblance between the 

 species, their definition and recognition is quite 



Fig. 1 121. \ beetle; 2, larva. difficnlt - Tlle following have been taken or per- 

 (After Packard.) haps occur in Indiana, 



KEY TO INDIANA SPECIES OF GYRINUS. 



a. Scutellum finely but distinctly carinate. 463. minutus. 



aa. Scutellum flat. 



b. Under side margin of thorax and epipleura brownish-yellow. 

 c. Under surface uniform brown or brownish-yellow. 

 (I. Larger, 6-7 mm. 



e. Polished black, not bronzed or iridescent. 464. fraternus. 

 ee. Black, very highly iridescent, margins and sides bronzed. 



f. Tips of elytra rounded ; form broader. 465. ventealis. 

 //• Ti PS of elytra truncate ; form more narrow. aquiris. 

 dd. Smaller, 4.5-5.5 mm. 



g. Form more elongate; tips of elytra rounded, covering only half 

 of last ventral segment. 

 h. Margins, sides and suture of elytra distinctly bronzed. 



466. .ZENEOLUS. 



lili. Elytra not at all bronzed. 467. dichrous. 



gg. Form short, broad; tips of elytra nearly truncate, almost or 

 wholly covering the last ventral segment. 468. limbatus. 

 gg. Under surface black or piceous, bronzed; last ventral segment red- 

 dish-brown. 



i. Upper surface finely alutaceous ; length 7-8 mm. 469. affinis. 



ii. Upper surface not alutaceous ; length 5.5 mm. 470. piceolus. 

 1)1). Under side margin of thorax and epipleura metallic black. 



j. Front margin of mesosternum regular in form. 

 k. Elytra highly polished, distinctly bronzed. 



I. Smaller and more narrow, 5-6 mm.; outer rows of elytral 

 punctures but little stronger than inner. 471. analis. 



II. Longer and broader, 7 mm. ; outer rows of elytral punctures 

 distinctly impressed. 472. borealis. 



klc. Elytra black, scarcely polished and not at all bronzed. 



473. LUGENS. 



jj. Front margin of mesosternum trilobed, with an oblique impression 

 each side; under surface black; length 5-6 mm. pectoralis. 



