540 On Aquatic Carnworous Coleoptera or Dytiscide. 
continuo, angulis posterioribus haud acutis ; prosterni processu angusto, fere plano. 
Long. 63, lat. 3 m.m. 
Though I have seen only a single very mutilated individual, I have no hesitation in 
considering it a distinct species allied to Platynectes eenescens, but making a greater 
approximation to Dytiscus decempunctatus (No. 763), it is narrower and more 
shining than P. znescens, and the reticulation of the elytra is closer but less regular 
and distinct, approaching in fact to D. decempunctatus in this respect ; the proster- 
nal process also is flatter and slightly broader than in P. zenescens, making also a 
slightly greater approach to that of D. decempunctatus ; the specimen decribed has 
lost its tarsi, but is probably a male. 
Tasmania. 819. 
Group 2. 
763. Dytiscus decempunctatus, Fab., Agabus decempunctatus, M.C_—Pervariabilis ; 
Ovalis vel oblongo-ovalis, fere levigatus, subtilissime reticulatus, per-nitidus, vel 
subopacus, niger, antennis pedibusque rufis, (posterioribus interdum piceis), plus 
minusve testaceo-signatus,capite szepius flavo-trimaculato ; thorace brevi, cum elytris 
omnino continuo, angulis posterioribus per-acutis, ad elytris arcte applicatis, 
margine laterali haud alto, sed nec obsoleto, angulis anterioribus szepius late flavis ; 
prosterni processu lato, fere plano, apice peracuto. Long 7, lat. 4 m.m. 
The male differs from the female by a slight incrassation of the basal joints of 
the front and middle tarsi, and these being set beneath with hairs which bear very 
minute palettes, the claws are small and simple ; the male also has the apical ventral 
segment provided with much coarser, oblique, stria-like rugosities than the female 
has. 
Australia (apparently throughout) ; Tasmania ; New Guinea; Ternate ; the Philippine Islands ; Java 
812. 
This is a very variable species, and some of its forms appear at first to have 
sufficient differences to justify their being considered distinct species ; the species 
is apparently very common in Australia, and the careful examination of a great 
many specimens from different parts of the country has shown me that the various 
forms are combined in one species by intermediate individuals. It is convenient to 
consider these forms as four in number, viz., the form which Germar described as 
Agabus spilopterus, of moderate size, about 7-77 m.m. in length and 4-44 m.m., in 
breadth, the anterior spot on the head is large and distinct, as is also the yellow mark 
at the front angles of the thorax, the upper surface is shining, and the hind legs 
are moderately long, and not very thick; the yellow marks on the elytra are a 
