TIIIC PKEIJACEDITS DIVIXC BEETI.KS. 231 



KJilY TO INDIANA SPECIES OF DYTISllS. 



". I.al>ruin distinctly eiiuirgiiiate at middle. 



h. Hind (-(jxal iivocesses rounded or acute, not spinuse. 



'■. Tliorax witli sides yellow, base and apex not or only indistinctly so. 

 <l. Abibiniinal sei,'nients reddish-l)ro\vu with a piceous hind margin; 

 elytra of female always siik-iite. 44!). fasciventris. 



(hi. Aliilominal segments unil'orm black or piceuus; elytra of females 

 smooth. 

 ''• Klytra without a narrow subapical eross4iar of yellow; smaller, 

 ;J.")-1!7 mm. 4ri0. iiviiKiin'S. 



''('. Elytra with a narrow oblique subapi<-al cross-bar; larger, ;'2- 

 ■'>r, mm. 451. verticalis. 



rr. Thorax with base and apex, as well as sides, distinctly and rather 

 broadly .yellow ; females dimorphic. 

 /. Hind coxal processes acute; length .'i:. mm. marginalts. 



//. Hind Cdxal processes obtuse; length 30 mm. sublimbatcis. 



hh. Hind coxal pro<-esses jii-oduced. distinctly s|)inose; thorax with base, 

 apex and sides iu-oadly yellow; lengtli ;')1-;35 mm. dauricus. 



(III. Labnnn nearly truncate at middle; tliorax with all the margins dis- 

 tinctly and bniadly yelliiw ; females dimor])hic. 451!. iiareisii. 



44!) (14.S1). I)-iTis(!us I'.^scivioN'i'uis Sa.v, Liaig's Exjied., II, 

 L'Til; ibid. I, 177. 

 Elong.ate-oTal. Greeuis'li-black abcivc; thora.x margined 

 with ycIliiw only on the sides, or with a taint trace of yel- 

 low at base and ai)ex. Elyti'a of female each with ten 

 grooves which reach beyond the middle; their apical third 

 linely and rather densely pun<tate. Length l'.^>-2,s mm. (Fig. 

 1 la ) 



Dekalb and iMarion c()unties; frequent. April 10- 

 Jnly 18. 



450 (17.^1i). Dytiscus hyi!riih;s Aubc. Spec. Gen., VI, is:is, IIG. 



I!e,gularly o\'at('. Tliorax shorter than in l'ii.<icii:ciitiiN. the apex usually 

 narrowly yellow and sometimes with a faint ,\elli.w line at l)ase. Pale mar- 

 gin of elytra of nearly ecpial width thr mgliout. Length 2(i-2S mm. 



Lake, Laporte, Stark-o, Vigo and Posey counties; frequent. 

 April lo-September 19. 



tfil (14s;!). Dytiscus verticalis Say. Trans. Amer. Phil. Soc, II, 1S2;!, 

 ill>; ibid. II, HOC. 

 ()\'al. rather broad. Thorax margined with yellow only on sides. Ely- 

 tra with three rows of well marked dorsal punctures; the marginal yellow 

 line narrowing on apical half, the subapical line often somewhat indistinct. 

 lA'Ugtb ;_!3-;!ri nun. 



Beach of Lake IMichij^an near .Millers, Lake County; scarce. 

 l\lav 2S. 



