864 On Aquatic Carnivorous Coleoptera or Dytiscide. 
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 tibize are slender, 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 isa short, more or less distinct 
prominence on the ridge at the point where the ligula exists in some other genera. 
The hind coxee have a very considerable anterior extension (as in most species of 
Celambus, ¢.g., Dytiscus parallelogrammus, No. 416). The terminal portions of 
the coxal lines are parallel, not turned outwards ; the hind legs are slender and 
their tibiz 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, asin that genus, the wing-cases are frequently 
denticulate at the tip; the broader hind portion of the epipleura separates the 
ageregate 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 recent immigrants to New Zealand and not really distinct 
species. 
I. 38.—Genus NECTEROSOMA. (Vide p. 413.) 
This is an aggregate consisting of eight species ; in many respects the individuals 
are similar to those of Antiporus, 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 joimts 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 
