1)14 On Aquatic Carnivorous Coleoptera or Dytiscidoe. 



by two rather elongate straight claws, which are closely applied to one another, 

 immobile, and subequal in length : when the outer face of the tarsus is carefully 

 examined it is seen to display a peculiar sculpture, consisting of coarse shallow 

 punctures, each of which bears a very adpressed elongate squama or scale, at the 

 hind margin of each joint these squamce are contiguous to one another, and form a 

 series of cilise overlapping the following joint. The front and middle legs are 

 slender and densely ciliate with very long hairs. Epipleura3 of elytra very reduced, 

 and not fitting closely to the margins of the body, except just at the shoulder, with- 

 out the least elevated line on their inner face. The basal ventral segment shows 

 at the side an elevated margin which is a little curved, and there is left between it 

 and the epipleura a considerable gap or opening : the epiplcura is here at its narrow- 

 est, and behind this opening again becomes slightly broader ; the upper edge of the 

 cpijileura is set, as it passes the third, fourth, and fifth ventral segments, with short, 

 rigid spines. The side pieces of the ventral segments are greatly reduced, that of 

 the first is peculiar ; it is bounded below by the curved raised line above described, 

 and this line in front is dilated and flattened out so as to form there a flat piece 

 which articulates directly with the hind border of the metathoracic epimeron ; 

 except for this anterior portion the rest of the side piece is almost membranous ; the 

 side piece of the second segment is still more membranous, and on the following 

 segments the side piece may be said to be reduced to an almost linear piece. 



The apical stigmata are peculiarly small. 



The male front tarsi are highly developed ; the three basal joints are dilated and 

 coadapted to form a circular plate, which beneath is fringed with cilia?, and bears at 

 the base two large cups, and on the rest of the surface dense glandular pubescence, 

 each hair of which is in fact a stalk, bearing a minute palette at its apex ; the 

 middle tarsi are undilated ; the females are without peculiar sexual sculpture, but 

 in one of the two species, they have a short impression near the lateral margin of 

 the wing-case about the middle. 



This genus is certainly one of the most interesting of the Dytiscidse, and its 

 detailed study will probably be attended with interesting results. The following 

 points are worthy of attention. First, the reduced wing-cases, colour, and soft 

 skeleton ; these should be compared with certain Ccelambi, {vide Hydroporus ennea- 

 grammus. No. 419) where we fi:nd a parallel condition. Second, the serrate edges 

 of the elytra are peculiar. Third, the direct articulation between the basal ventral 

 sidepiece and the metathoracic epimeron. Fourth, the peculiar sculptured hind 

 tarsi. Fifth, the development of the hind coxre, and the ciliation of front and 

 middle legs, carried to a greater extent than in any other water-beetle ; and, sixth, 

 the beautiful development of a band of transverse pubescence on the upper face 

 of the hind femur. 



This combination of points of peculiar interest indicates a very isolated ancestral 

 record, and peculiar habits. 



