692 On Aquatic Carnivorous Coleoptera or Dytiscide. 
specimens from tropical Africa, show the characters of the Madagascar form except 
that they are still less different from what I have called the typical form. 
Widely distributed. Australia and New Caledonia, Formosa, China, Siam, Arabia, Madagascar, 
Lake N’Gami, Senegal. 976. 
I. 74.—Genus GRAPHODERES. 
Coxal lines fine but distinct ; supra-articular border moderately broad ; middle 
femora with rather short, stout sete. Elytra uniformly speckled with black and 
yellow. 
The eleven species form two groups, the first represented only by a single species -— 
1. Form rather depressed ; thorax and head without any distinct black marks. 
No. 1084. 
2. Form rather convex; thorax and head with very distinct black marks. 
Nos. 1085 to 1094. 
Group 1. 
1084. Dytiscus liberus, Say, Hydatieus liber, M.C.—Ovalis, parum elon- 
gatus, fere depressus, nitidus, ferrugineus, prothorace ad latera elytrisque testaccis, 
his creberrime nigro-vermiculatis. Long. 12, lat. 7 m.m. 
In the male the front tarsi are provided beneath with three larger palettes of 
unequal size, and sixteen smaller but still highly developed ones. The middle 
tarsi have the basal jomt just perceptibly thickened, and furnished beneath with 
four palettes—two outer and two inner—while the second joint bears only two 
palettes, which are placed at its outer margin. 
The species has much resemblance to a species of Rhantus, from which a glance 
at the ciliate hind margins of the posterior tarsi will, of course, distinguish it: it 
varies somewhat in size, but not much in other respects. 
United States of North America, from Vancouver’s Land to New York and Florida. 989. 
Group 2. 
1085. Hydaticus austriacus, Sturm, M.C.—Nitidus, testaceus, vertice, signaturis 
frontalibus prothoracisque fasciis duabus magnis, nigris, elytris creberrime nigro- 
vermiculatis ; elytrorum epipleuris pone medium per-angustis ; tarsis posterioribus 
gracilibus. Long. 13, lat. vix, 8 m.m. | 
