THE CANADIAN ENTOMOLOGIST. 



epimeron does not articulate with the metasternum, and thus allows the 

 episternum of the latter to reach the cavity. These features are not, as a 

 rule, difificult to make out from specimens, and form the basis of the 

 modern classification of the family. Both figures, which are taken from 

 Dr. Sharp's memoir, are lettered alike, ms. being the mesosternum proper, 

 ms. eps. its episternum and epip. the epipleura. Of the Dytisci fragmen- 

 tati only one genus is recorded in the Canadian list, /. e. : 



Laccophilus, Leach. 



This includes two species from the fauna under consideration, both 

 of which are rather small, very active beetles of ovate form and pale 

 colour, in which yellowish or testaceous predominates. They separate thus : 

 Larger (.24 in.), head, thorax, legs and under surface testaceous ; 

 elytra dark, with the margin and four submarginal spots (sub- 

 humeral, median, post median and subapical) yellowish, also with 

 three irregular yellowish basal marks and a narrow sutural 



line maciilosus, Germ. 



Smaller (.20 in.), pale ; elytra with the subhumeral mark of maculo- 



sus, the others confused proximus. Say. 



The Dytisci complicati form the bulk of the Canadian fauna in this 

 family, and may be conveniently divided into four tribes as follows, in 

 order to avoid a long and complicated synoptic table : 

 A. Prosternum deflexed between the front coxae, front and middle tarsi 



four-jointed or apparently so, small species Hydroporini. 



AA. Prosternum not detiexed ; tarsi distinctly five-jointed. 



b. Front tarsi of males with three* basal joints dilated, forming an 



oblong or elongate surface Colymbetini. 



bb. Front tarsi of males dilated so as to form a rounded or trian- 

 angular disk. 



Posterior pairs of spiracles large, transverse ; $ anterior 

 tarsal disk rounded, the cupulas of unequ il size. Pos- 

 terior tarsi with two nearly equal claws except in 



Hydaticus Dytiscini. 



Posterior pairs of spiracles small, anterior tarsi of ^ forming 

 a subtriangular disk having four rows of small, equal 

 cupules. Hind tarsi with one claw or very unequal 

 claws Cybistrini. 



*There are only two in A^abinus, 



