THE CANADIAN ENTOMOLoaiSl'. 69 



THE COLEOPTERA OF CANADA, 



BY H. F. WICKHAM, IOWA CITY, IOWA. 



viii. The Haliplid.e and Dytiscid^e of Ontario and Quebec. 



. The above-mentioned families of carnivorous water beetles are taken 

 up here by request of the Editor and Committee, because of the great 

 difficulty most students of Coleoptera, especially if they are beginners, 

 find in identifying any of their captures in these groups, or even in sep- 

 arating the species with approximate accuracy. It is to be feared that 

 with many it will prove difficult to follow the tables herewith presented ; 

 but they have been made as plain as circumstances will allow, and care 

 has been taken to follow the best authorities in the selection of char- 

 acters supposed to mark the respective species, so that by diligent atten- 

 tion to details the user of the paper may hope to co-relate his collection 

 with our lists. 



The Haliplid/e which may be considered first, includes a small 

 number of beetles easily recognized by the very convex body, narrowed 

 and often pointed before and behind ; in colour yellowish, with numer- 

 ous black spots on the thorax and elytra. The antennas are ten-jointed, 

 situated on the front before the eyes, glabrous and filiform ; the legs are 

 slender, not fitted for vigorous swimming, the hind coxae furnished with 

 broad plates, contiguous internally, which conceal the posterior legs at 

 their basal half, and from three to six ventral segments. These little 

 creatures, which, from their peculiar spotted appearance, suggest aquatic 

 lady-birds, may be found very commonly during the summer in ponds 

 where plant life abounds, especially Algje. On account of their feeble 

 swimming power they are easily captured by raking the mass of vegetable 

 matter on to the bank, when the beetles, on crawling out to regain the 

 water, may be secured. 



Only two genera are represented in Canada : Haliplus, which has 

 the elytral interstices punctate and the last joint of the palpi small, 

 subulate, and Cnemidotiis, without interstitial elytral punctures, the 

 terminal palpal joint conical, longer than the third. The species are 

 difficult to define ; the following characters, however, are those accepted 

 as specific by Mr. Crotch, in his " Revision." 



Haliplus, Latr. 

 A. Thorax without basal impression ; larger species. 



b. Head with bilobed black spot on the vertex; elytral striae not 

 deeper at base (.15 in.) cribrarius, Lee. 



