TIIK I'KKDACKOUS DIVING BKKTT.KS. 



231 



KEY TO INDIANA SPECIES OF DYTISCUS. 



. Labniiu distinctly emarginate at middle. 



1>. Hind coxal processes rounded or acute, not spinose. 



c. Thorax with sides yellow, base and apex not or only indistinctly so. 



<L Abdominal segments reddish-brown with a piceous bind margin; 



elytra of female always silicate. 4411. FASCIVENTRIS. 



(hi. Abdominal segments uniform black or piceous: elytra of females 



smooth. 



c. Elytra without a narrow subapieal cross-bar of yellow; smaller. 



25-27 mm. 450. HYURIDUS. 



<(-. Elytra with a narrow oblique subapieal cross-bar; larger, 32- 



35 mm. 451. VERTICALIS. 



(<. Thorax with base and apex, as well as sides, distinctly arid rather 



broadly yellow; females dimorphic. 



/. Hind coxal processes acute; length .",:'. mm. MARGINALIS. 



ff. Hind coxal processes obtuse; length 30 mm. SUBLIMBATUS. 



1>1>. Hind coxal processes produced, distinctly s]>inose; thorax with base, 

 apex and sides broadly yellow ; length Ml-. 1 !.! mm. DAURKTS. 



IKI. Labrum nearly truncate at middle; thorax with all the margins dis- 

 tinctly and broadly yellow; females dimorphic. J5i'. IIARRTSII. 



44!> (14S1). DYTISCTS KAXCIVENTIMS Say. Long's Exped.. II. 

 2T(: ibid. I. 177. 



Elongate-oval. (Jreenish-black above; thorax margined 

 with yellow only on the sides, or with a faint trace of yel- 

 low at base and apex. Elytra of female each with ten 

 Amoves which reach beyond the middle; their apical third 

 finely and rather densely punctate. Length 25 i'S mm. (Fig. 

 11G.) 



Dekalb and Marion comities; frequent. 

 July 18. 



April 10- 



Fig. 116. 

 Natural size. 



450 (1782). DYTISCUS HYBRIDUS Aube, Spec. Gen., VI, 1S3S, 11G. 



Regularly ovate. Thorax shorter than in f<ix<-i rent fix, the apex usually 

 narrowly yellow and sometimes with a faint jellow line at base. Pale mar- 

 gin of elytra of nearly equal width thr.iughout. Length 2<>-2.x mm. 



Lake, Laporte, Starke, Vigo and Posey counties; fre<|uent. 

 A]>ril 15-September 10. 



4.11 (14s:>>). DYTISCUS VERTICALIS Say. Trans. Amer. 1'hil. Soc.. II. 1S{. 

 1)2; ibid. II. r.oti. 



Oval, 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 subapieal line often somewhat indistinct. 

 Length 33-35 mm. 



Beach of Lake Michigan near Millers. Lake County; scarce. 

 May 28. 



