864 On Aquatic Carnivorous Coleoptera or Dytiscidm. 



I. 37.— Genus ANTIPORUS. {Vide p. 410.) 

 Eight species form this aggregate ; the individuals are in colour a mixture of 

 black and yellow, in a rather indefinite and variable manner : the form is oblong- 

 oval, moderately convex beneath, the surface is densely and evenly punctured both 

 on the upper and under sides, and is not shining, and bears an excessively minute, 

 scarcely visible pubescence. The eyes are convex and prominent ; the portion of 

 the head in front of them is very short, its front edge is variable in form but does 

 not possess a raised margin. The anterior tibiae are slendei% and their tarsi usually 

 have the joints elongate, and narrow at the base, the third being deeply bilobed, 

 the real fourth joint not visible, the terminal (apparent fourth) joint elongate, and 

 inserted near the base of the third joint. The posterior portion of the epipleura is 

 rather broad, there is no definite genicular area, the epipleura being punctured up 

 to the point where it becomes contiguous with the prothorax : on the inner face 

 of the wing-case there exists a well-marked ridge ; this is not developed into any 

 distinct ligula near the apex, although there is a short, more or less distinct 

 prominence on the ridge at the point where the ligula exists in some other genera. 

 The hind cox« have a very considerable anterior extension (as in most species of 

 Coelambus, e.g., Dytiscus parallelogrammus, No. 416). The terminal portions of 

 the coxal lines are parallel, not turned outwards ; the hind legs are slender and 

 their tibiae are punctate externally. The external sexual disparities are nearly 

 confined to the legs, the males are usually in this respect remarkable. 



The species of this aggregate in form and sculpture, and even in colour, approxi- 

 mate to the Deronecti of Europe, and, as in that genus, the wing-cases are frequently 

 denticulate at the tip ; the broader hind portion of the epipleura separates the 

 aggregate from most of those near it, but approximates it to Chostonectes, from 

 which it differs by the shape of the front tarsi, which have always an elongate 

 terminal joint, as well as by numerous minor characters, amongst which the fine 

 dense sculpture of the under surface is conspicuous. 



These insects are found only in Australia, Tasmania, and New Zealand : the 

 species from the latter locality are very closely allied to Australian species, and it 

 is possible they may be Z'ecent immigrants to New Zealand and not really distinct 

 species. 



I. ^Q.—Genn& NECTEROSOMA. {Vide ^. 413.) 



This is an aggregate consisting of eight species ; in many respects the individuals 

 are similar to those of Antijjorus, but they differ in some important points, and one 

 of these — the structure of the anterior tarsi — distinguishes the aggregate from all 

 its near allies; all the five joints are distinctly visible ; the third joint is not truly 

 bilobed, but only emarginate at its outer portion, and the small fourth joint pro- 

 jects quite distinctly beyond it, and is therefore conspicuous between the third and 



