806 On Aquatic Carnivorous Coleoptera or Dytiscidae. 



froiu their form and details, a likeness to the aberrant group of Carabidte, Pseudo- 

 niorphini, 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, II, 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 presternum 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 epipleurje 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 Cybister. 



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 is 

 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 j^alpus presents a similar structure, but more exaggerated, 

 the joint being broader, and one side of the apical 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 nietasternum bears in front a 

 rather elongate, narrow, well developed cavity. The hind coxie are very large and 

 their anterior border is excessively large, so that although the metastei'nuni is 

 elongate in the middle, it possesses only short side wings, and these are deflexed 

 outside the front border of the coxse 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 coxjb, their divergent 

 anterior portions running parallel to, and at a considerable distance from, the front 



