On Aquatic Carnivorous Coleovtera or Dytiscidoe. 649 



Group 1. — Serial punctures on the upper face of the hind tibia distant from one 

 another, and quite parallel with the outer border of the tibia ; series 

 of punctures on the upper face of the hind femur consisting of 

 isolated non-pubescent punctures ; front of head not quite so short 

 as, and eyes rather smaller than, in the otlier groups ; Nos. 1006 to 

 1014. 



Group 2. — Serial punctures on the upper face of the hind tibia more or less 

 approximate to one another, and not perfectly parallel with the outer 

 margin, the antei-ior being placed rather further from the outer 

 border than the terminal ones are ; series of punctures on the upper 

 face of the hind femur, dense and crowded together, forming a finely 

 pubescent band ; pattern of upper surface variable, but never consist- 

 ing of one or two quite definite longitudinal pale vittae ; middle tarsi 

 of male a good deal dilated; Nos. 1015 to 1043. 



Group 3. — Pattern of upper surface of wing cases consisting of one or two quite 

 reofular loncjitudinal vittse ; middle tarsi of male but little incrassate ; 

 Nos. 1044 to 1051. 



The groups cannot be considered either natural or distinct; thus No. 1015 is 

 quite intermediate between the first and second groups, and No. 1044 will probably 

 prove an equally perfect connection between the second and third. 



Besides the species enumerated in the text, the following descriptions probably refer to species of this 

 genus: — Hydaticus apicalis, Boh. (No. 1,305 huj. op.) near No. 1,041; CafTraria. — Hydaticus 

 aruspex, Clk. (No. 1,306) ; China.— Hydaticus caffer, Boh. (No. 1,308) near No. 1,042 ; Caffraria.— 

 Hydaticus discoidalis, Hope (No. 1,310)? No. 1,029 var. ; Africa. — Hydaticus fulvo-notatus, Clk. (No. 

 1,311); Africa. — Hydaticus histrio, Clk. (No. 1,312); India. — Hydaticus lateralis, Cast. (No. 1,313); 

 South America. — Hydaticus madagascariensis, Aub6 (No. 1,314) ; Madagascar. — Hydaticus nauzieli, 



Fairm. (No. 1,315) ?=No. 1,032; France. — Hydaticus nigro-marraoratus, Clk. (No. 1,31G); Angola. 



Hydaticus nigro-\'ittatus. Clk. (No. 1,317) ?=No. 1,028; Japan. — Hydaticus paganus, Clk. (No. 1,318); 

 Africa. — Hydaticus phUippensis, Wehncke, (No. 1,319); Philippine Islands. — Hydaticus usheri, Clk. 

 (No. 1,321); Africa. — Hydaticus verecundus, Clk. (No. 1,322)? South America. — Hydaticus 

 xanthomelas, BruUe (No. 1,323) ; South America. The systematic position of the following is more 

 doubtful, but may be in Hydaticus: Colymbetes trivittatus, Mont. (No. 1,255) ; Woodlark Islands. — 

 Dytiscus flavo-cinctus, Guer. (No. 1,290); Papua.— Dytiscus unifasciatus. Fab. (No. 1,296) ; Africa. 



