1288 FAillLT T. GTEIXID.^. 



aa. Last ventral elongate, conical; labrum prominent; scutellum Invisible; 

 length fi mm. Gybetes. 



I. Gyrinus Linn. 173-3. (Gr., "a circle or ring.") 



Our member.s 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 

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

 On account of the close resemblance between the 

 species, their definition and recognition is cpite 

 difficult. The fol]o^\ing have been taken or per.- 



Fig. 121. 1, beetle; 2, larva. . _ t 



(After Packard.) haps occur in Indiana. 



KEY TO IXDIAN.V SPECIES OF GYRINt'S. 



.(. Scutellum finely but distinctly carinate. 463. minttl-s. 



'/((. Scutellnm flat. 



h. t'uaer side margin of thorax and epipleura lirdwuish-yellow. 

 c. Uniler surface uniform brown or limwnisli-.vellow. 

 il. Larger. 6-7 mm. 



c. I'olished black, not bronzed or iridescent. 4CA. fbaternus. 



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



f. Tips of elytra rounded; form broader. inr,. vextr.^ijs. 



ff. Tips of elytra truncate; form more narrow. aquiris. 



(1(1. Smaller, 4..5-.J.5 mm. 



g. Form more el<iu,t;ate; tips of elytra rounded, covering only half 

 of last ventral segment. 

 h. Margins, sides and suture of elj-tra distinctly bronzed. 



40(3. .EXEOLUS. 



7(7). Elytra not at all bronzed. 467. dichbous. 



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

 wholly covering the last ventral segment 46.S. limbatus. 

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

 dish-brown. 

 ;. Upper surface finely alutaceous; length 7-S mm. 4G0. affixis. 

 a. Upi>er surface not alutaceous; length .5.5 mm. 470. piceoeus. 

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

 /. Front margin of mesosternum regular iu form. 

 7r. Elytra highly polished, distinctly bronzed. 



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



punctures but little stronger than inner. 471. axalis. 



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



distinctly impressed. 472. borealis. 



7i7i-, Elytra black, scarcely polished and not at all bronzed. 



473, LfGEXS. 



;■/. Front margin of mesosternum trilobed, with an oblique impression 

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



