iiii; cii'AW i.iNc \\Aii;i; r.ia; I'l.i'is. -01 



they may often be noted crawling slowly over the partially decayed 

 aquatic plants, especially al<ia\ On account of their feeble swini- 

 ining powers they n!a>- be easily captured by ral<ing the mass ol" 

 vegetable matter oni.i llir I)ank, \\Ii(mi llic beetles, on crawlinu' oul 

 to regain the water, may be secured. The name of the familv' is 

 derived from the Greek and means "sailing the sea," or "covered 

 with Avater." 



The larva? of the TIalii)lidji' live in the same places as the adults. 

 They aie composed of slender segments, each, except the head, 

 being furnished on the back with fleshy lobes, bearing spiny tips,- 

 while the last segment is extended into a long tapering appendage. 



The lu'incipal paper, including descriptions of the North Ameri- 

 can species of this family, is by 



Crotch. — "Revision of the Dytiscidae of the TTnited States," in 

 Trans. Amer. But. Soc, TV. 187-^. 388-385. 



The North Amei-ica!] sj^ecies are (livid"d among thi-ee genei'a, 

 two of which are represcMiled in Indiana. 



KKY TO INDIANA (iENKKA OF IIALJPLID.O^:. 



It. 'reriuiiinl .jniiif of jialpi small, awl-shaped; intervals of el.ytra piiiiclal(>; 



thorax without black spots at base. I. Haiji'ms. 



(/(/. 'renniual .ioiiit of palpi conical, longer than the third; intervals of ely- 



Ira without punctures; thorax with two small round impressed black 



spots at base. II. Cnemidotis. 



I. Haliph-s Latr. ISOti. ((Jr.. "the sea f sail.") 



Of the ten species of this genus known from the ITnited Stales, 

 six have been tak'en in Indiana, while another may occur. 



Ki:V TO INDIANA SPKCIKS OK TIAI.il'I.rS. 



(I. Thorax without a l»asal im]iression. 



b. Prosternum niai-uined at sides; elyti'al iiuiictures deeiier al base tliau 

 apex. 

 (\ A distinct black sjiot on middle of fronl mars^in of thorax. 



."'.S:'.. TKiorsis. 

 CC. Thorax without Itlack sjiot, sometime.'^ sliiilitly darker at apex. 

 (J. Elytra not sinuate near apex. 



r. Spots of el.ytra distinct; size lar.uer. ;*>.5^i mm. kascia'its. 



re. Spots more or lt>ss coiifJuenl ; size smaller. 2..1 mm. 



3f^4. LEW isii. 

 (1(1. Elytra distinctly sinuate near apex: spots often slightly con- 

 nected lint not conllncni. 885. borf.ai.ts. 

 1)1). I'rostei-num tlat. not niar^iiied al sides; elytral imnctures not deeix'r 

 at base than a|iex; elylra dull l)r(i\\nish-yello\v with elongate black 

 spots. o8(i. ciubarhs. 



