On Aquatic Carnivorous Coleoptera or Dytiscide. 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 other 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 anterior 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 vittse ; 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 
recular longitudinal vittz ; 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; Caffraria.—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, Aubé (No. 1,314) ; Madagascar.—Hydaticus nauzieli, 
Fairm. (No. 1,315)’=No. 1,032; France.—Hydaticus nigro-marmoratus, Clk. (No. 1,316); Angola.— 
Hydaticus nigro-vittatus, Clk. (No. 1,317)?=No. 1,028 ; Japan.—Hydaticus paganus, Clk. (No. 1,318) ; 
Africa.—Hydaticus philippensis, Wehncke, (No. 1,319); Philippine Islands.—Hydaticus usheri, Clk. 
(No. 1,321); Africa.—Hydaticus verecundus, Clk. (No. 1,322)? South America.—Hydaticus 
xanthomelas, Brullé (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. 
