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VOL. XXVII. LONDON, MAY, 1895. No. 5. 



THE COLEOPTERA OF CANADA. 



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



IX. The Dytiscid^ (Colymbetini) of Ontario and Quebec. 

 The Colymbetini, which follow the Hydroporini in Dr. Leconte's 

 scheme, are immediately distinguished therefrom by the distinctly five- 

 jointed tarsi, and also, as a rule, by the much greater size. The males 

 have the anterior, or middle tarsi, variously modified, but not forming 

 regularly rounded disks as in the following group. Using the characters 

 developed by the writers, whose works have already been mentioned, we 

 may divide the Canadian genera thus : — 

 A. Semimembranous side pieces of first dorsal segment smooth. 

 b. Hind tarsi with unequal claws. 



Black or metallic above Ilybius. 



Ferruginous above Matus. 



bb. Hind tarsi with claws equal or nearly so. 



c. Last joint of palpi emarginate Coptotomus. 



cc. Last joint of palpi normal. 



d. Elytra deeply lo-striate Copelatus. 



dd. Elytra not regularly striate. 



e. Prothorax not margined ; elytra with numerous 

 very short minute longitudinal stripe .... Agabetes. 

 ee. Prothorax margined at sides. 



Wing of metasternum linear, strongly 



curved Ilybiosoma. 



Wing of metasternum wedge-shaped Agabiis. 



AA. Semimembranous side pieces of first dorsal rugose. Species usually 

 large. 



Elytra reticulate Scutopterus. 



Elytra smooth or with short coarse lines ; metasternum with deep 



groove Rhaiitus. 



Elytra transversely strigose ; metasternum with feeble 



groove Colymbetes, 



