540 On Aquatic Carnivorous Coleoptera or Dytiscidw. 



continue, angulis posterioribus haud acutis ; prosterni processu angusto, fere piano. 

 Long. 6t, lat. 3f m.m. 



Though I have seen only a single very mutilated individual, I have no hesitation in 

 considering it a distinct species alUed to Platynectes senescens, but making a greater 

 approximation to Dytiscus decempunctatus (No. 763), it is narrower and more 

 shining than P. senescens, 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. aenescens, 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. 



Guoup 2. 



763. Dytiscus decempunctatus, Yah-jAgahus decempunctatus, M.C. — Pervariabilis ; 

 Ovalis vel oblongo-ovalis, fere Isevigatus, subtilissimc reticulatus, per-nitidus, vel 

 subopacus, niger, antennis pedibusque rufis, (posterioribus interdum piceis), plus 

 minusve testaceo-signatus,capite saspius flavo-trimaculato ; thorace brevi, cum elytris 

 omnino continuo, angulis posterioribus per-acutis, ad elytris arete applicatis, 

 margine laterali haud alto, sed nee obsolete, angulis anterioribus spepius late flavis ; 

 prosterni processu lato, fere piano, 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 ; Temate ; 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 1-7h m.m. in length and 4-4^ 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 



