Tlir: WATER SrAVENGER BEETLES. 



255 



" ii M-)"^'."). TTvDROi'nin s OVA-US Zir.ii. Tr •<•. I'liil. Aciul. Nut. Sci.. II, 

 IS 14, 45. 



Less elonsiile. more convex. Above bliuU witli :iii olive tinge; beneath 

 pi((>ons; antennio and tarsi paler. Abdomen pubescent, the last three seg- 

 iiiriits narrowly smooth at middle, without yellow spots at sides. Pro- 

 -iiM-nal prominenco, in whicli front end of sternal spine fits, open in front. 

 I.cn:j;th 31-3o nun. 



Sloutlioni linlf of State; fre(inent. May 25-Oct()l)or 8. Often at- 

 liaetod by electi'ic liffht. 



•I'.ll (15SG). IIVDKOIMIILLS TUIANGULARIS 



S;iy. .Tourn. Phil. Acad. 



Nat. Sci., III. 1823, 201 ; 



ibid. II, 128. 

 More elongate, less convex. Above of 

 same hue as oratiis; beneath darker. 

 UK ire shining, the abdominal segments 

 with more or less distinct triangular 

 yellow spots at sides. First segment pu- 

 i"-cent. the remainder broadly smooth 

 1 1 middle. Prosterual prominence closed 

 in front. Length 34-37 mm. (Fig. 12G.) 

 Throughout the State; common. 

 M;ireh 19-October 27. Sometimes 



.ittraeted bv thousands to electric Fig- 126. 6 H. tmngul iris Say natural size: 



/, antenna; g, front tarsus of female; h, same ot 

 iio'htS in Indianapolis and the male, all magnified;^,^uk view of stomal spine. 



l.-irger cities. Hibernates as imago. 



VI. Tropisterncs Sol. 1884. (Gr.. "keeU breast.") 



Smooth, shining, oval insects, mostly black above; very connnon 

 in ponds, lakes and slow-flowing streams. Nine species, including 

 \()s. 1588 to 1505 of the Henshaw "Catalogue." belong to this 

 genus, five of which have been taken in Indiana. 



KEY TO INDIANA SPECIES OF TROPISTERNIS. 



a. Prosternal prominence or groove closed in front; elytra without yellow 

 stripes. 

 1). Thorax and elytra oju'rowly manzined with yellow. 



492. NIM15ATI s. 



bb. Thorax :\nd elytra entirely black above. 



c. Front part of sternal crest very finely and indistinctly puncturi>d : 

 elytra with very fine and coarser punctures intermixed. 



493. MixTUS. 

 cc. Front i::irt ;if sternal crest distincfly punctured: olytral inuictures 

 equal in size or nearly so. 

 d. F(n'm elongate-oval: olytral ptnictnres very minute and indis- 

 tinct. 494. sntL.Evis 



117—23402] 



