On Aquatic Carnivorous Coleoptera or Dytiscidce. 865 



fifth joints. The coxal Hnes have their terminal portions much turned outwards, 

 and in their anterior parts are much less widely separated from one another than 

 they are in Antiporus. The ligula on the inner face of the elytra is quite distinct 

 although short and broad. The characters in other respects are much those of 

 Antiporus. 



The genus is peculiar to Australia and Tasmania. 



I. 39.— Genus MACROPORUS. {Vide p. 416.) 



This is an aggregate consisting of six species ; the individuals are of large size 

 amongst their allies, the largest attaining 7 m.m. of length, but vary much in 

 width, they are convex beneath ; the upper surface is distinctly pubescent, the lower 

 is coarsely punctured : the size attained is greater than in any other Hydroporini, 

 and equals that of the members of the Hyphydrini. 



The hind coxse have a large area, and are elongate even quite near the middle 

 longitudinally of the body, their anterior border does not stretch abruptly forwards, 

 so that the length of the coxa at its longest part is not twice what it is at its shortest 

 pan ; the coxal lines are subparallel, being a little divergent both in their anterior 

 and posterior portions ; and their articular cavities are but slightly separated ; the 

 femora are broad and sublaminate (showing when viewed from above a distinct 

 lamina at their outer hinder portion, which when the tibia is flexed receives and 

 covers its base : the hind tibiae are glabrous externally, with a series of setigerous 

 punctures near the margin : the epipleura of the wing-case is moderately broad in 

 its terminal portion, and is impressed at the humeral angle, but there is no trace of 

 any raised line limiting externally this area : there is no ligula on the inner 

 face of the wing-case : the real fourth joint of the front tarsus cannot be perceived. 



The genus is especially characterized amongst the Hydroporini by the well 

 developed swimming legs, these organs attaining in Macroporus a perfection greater 

 than in any other Hydroporini. In some other respects there is considerable 

 variety amongst the species ; M. lateralis, has the terminal joint of the front tarsus 

 quite short, and in fact approximates to Hyphydrus by the structure of this part, 

 while the other species have the joint alluded to either considerably or greatly more 

 elongate. 



The species are found only in Australia and Tasmania. 



I. iO.— Genus DERONECTES. (FiJe p. 418.) 



Group 1. 



The characters assigned to the first group of species of Deronectus (see p. 419), 



justify the association together of about twelve species, which when carefully 



examined exhibit nevertheless important structural differences amongst themselves : 



