318 



On Aquatic Carnivorous Coleoptera or DytiscidcB. 



Prostemal pro- 

 cess on same 

 plane of di- 

 rection as the 

 prosternnni ; 

 front tarsi 5- 

 jointed. 



Inferior spur of 

 hind tiliia not, 

 or but little, 

 liroader than 

 tlie other. 



Hind margins of 

 joints of pos- 

 terior tarsi not 

 set with flat- 

 tened and ad- 

 pressed cili». 



'Stigmata of last two 

 dorsal segments not, 

 or but little, broader 

 than the preceding 

 ones ; outline of eye 

 notched by the free 

 margin of front of 

 head. 



Stigmata of last two" 

 dorsal segments en- 

 larged, each on the 

 penultimate seg- 

 ment being about 

 one-fourth of total 

 breadth of the seg- 

 ment ; circular out^ 

 line of eye uninter- 

 rupted. 



Hind margins of ) 

 joints of pos 

 terior 

 provided 

 tern ally 

 flattened 



tarsi 



ex- '(■ 

 with I 



ad- 



1^ pressed cilise. ) 



Inferior spur of) 

 hind tibia di- 1 

 lated, much (• 

 broader than | 

 the other. J 



COLYMBETIDES. 



(Fn/ep. 490.) 



Dytiscini. 

 (Firfep. 632.) 



HYDATICIDES. 



{Vide p. 647.) 



Cybistrini. 

 ( Vide p. 700.) 



I. 16.— Genus AMP HI ZU A. 



Antennae with the seven or eight basal joints more or less distinctly punctate, 

 the others glabrous and shining. Hind coxae connected to the nietasternum by a 

 nearly straight transverse suture ; nietasternum marked in the middle behind by 

 an indistinct transverse suture. 



The three rare species are found in the western parts of North America. 



176. Amphizoa insolens, Leconte, M.C. Tom. 1. — Nigro-picea, sine pubesceutia, 

 opaca, rugulosa ; thorace elytris multo angustiore, lateribus serrulatis, pone medium 

 sinuatis, angulis posterioribus acutis, medio longitudinaliter canaliculato ; elytris 

 punctato-rugulosis, sat distincte striatis ; prosterni processu brevi, lato. Long. 

 11 J, lat 6 m.m. 



North America (California). 232. 



177. Amphizoa josephi, Matthews, Cist. Ent. 1, p. 119. — Nigricans, sine 

 pubescentia, opaca, subdepressa ; thorace elytris multo angustiore, lateribus 



