896 On Aquatic Carnivorous Coleoptera or Dytiscide. 
from their form and details, a likeness to the aberrant group of Carabidee, Pseudo- 
morphini, but I am not able to find any real approximation. There is however a 
decided although not close approximation to Platambus. 
The genus as here defined comprises one North American, and two Australian 
species. Hamlet Clark (Journ. of Entomology, I, p. 15,) proposed a distinct generic 
name, Batrachomatus, for the Australian species known to him, but I do not think 
it is advisible at present to separate the Australian from the North American 
species ; the only differences I can see are that in the Australian Batrachomatus 
wingi, Clk., the prosternum is not so deeply sulcate, and the coxal lines are quite 
parallel in front, the coxal border is broader, and there is a distinct, although 
small coxal notch, and the epipleuree are rather broader. It is quite probable 
however that ultimately the North American may have to be separated from the 
Australian species, and in that case the name Clark proposed will be useful. 
. I. 59.—Genus COPTOTOMUS. (Vide p, 601.) 
This aggregate comprises three species; their individuals are of narrow, oval, 
rather convex form, and red or yellow in colour, with black marks on the upper- 
surface. ‘The terminal joint of the palpi (more especially of the labial) is broader 
than the other joints and notched or emarginate at the extremity. The middle of 
the prosternum is greatly thickened so as to present a vertical front part, somewhat 
as in Uybister. 
The prothorax is margined at the sides. Viewed in one direction, the terminal 
joint of each palpus, looks slender and slightly pointed towards the extremity, but 
viewed from a direction at right angles to this, the last joint of the maxillary palpus 1s 
seen to become slightly broader from the base to the apex, and its apical margin to 
be emarginate, one side of the notch being more projecting than the other; the 
apical joint of the labial palpus presents a similar structure, but more exaggerated, 
the joint being broader, and one side of the apicai portion of the joint being greatly 
larger than that on the other side of the notch. The prosternum is very incrassate 
along the middle, so that it presents in front a distinct vertical edge at right angles 
to its longitudinal axis of direction ; the prosternal process is rather elongate, and 
is acuminate, and at the sides finely margined, but is so much compressed that its 
margin is concealed ; the inter-coxal process of the metasternum bears in trout a 
rather elongate, narrow, well developed cavity. The hind coxve are very large and 
their anterior border is excessively large, so that although the metasternum is 
elongate in the middle, it possesses only short side wings, and these are detlexed 
outside the front border of the coxee as narrow parallel-sided bands. The coxal 
lines are rather fine but are perfectly distinct, they are widely separated, and in 
front much divergent, they do not reach the front border of the coxee, their divergent 
anterior portions running parallel to, and at a considerable distance from, the front 
