On Aquatic Carnivorous Coleoptera or Dytiscide. 8L1 
The ventral sutures are very deep, that between the second and third abdominal 
segments very deep even in the middle. 
The sexual distinctions are very slight. The only species known has been found 
in Cayenne. 
I. 13—Genus DEROVATELLUS. (Vide p. 286.) 
This is an autogenus;; the insect is of the size of an average Hydroporus, and 
has much the appearance of the species of that genus; the upper surface is densely 
and rather finely punctured. The prosternal process is short and broad, rhomboidal 
in form, with its extremity received between the middle cox; these are exposed, 
and contiguous. The mesosternum is placed at a slightly obtuse angle with the 
metasternum, and is not much exposed: the coxal lines are a little divergent in 
front, but not much separated, and are indeed approximate through their whole 
length, they are however distinctly turned outwards in their terminal portion ; the 
coxal border has very little extension in the transverse direction. The posterior 
trochanters are normal, as are also the ventral sutures, that between the second and 
third segments being quite obliterated in the middle: the claws of the front tarsi 
are excessively minute. The sexual distinctions are very slight. 
The insect inhabits tropical America. 
I. 14.—Genus LACCOPHILUS. (Vide p. 287.) 
About eighty species compose this aggregate. They are insects of small size, the 
largest attaining only 6 m.m. of length; the upper surface is frequently more or 
less variegate, though generally in an indefinite manner, and its sculpture is either 
slight, or wanting, giving place to a very polished surface, the underside is free 
from sculpture except that there are elongate, oblique scratches on the ventral 
seoments ; the form varies from nearly elliptical to an oval, and is never very 
convex, the outline is very continuous. 
The bead is very short and broad, the portion in front of the eyes being extremely 
short, the eyes of moderate size have their circular inner outline only very obscurely 
infringed on at the insertion of the antennze: the head in front shows no trace 
of a raised margin, its emarginate-truncate front edge being very thin and closely 
applied to the exposed labrum. The antenne are slender and quite symmetrical, 
showing no peculiar forms or sexual differences ; the parts of the mouth are small 
and the palpi simple. The thorax is without any lateral margin, and almost 
without any punctures along the margins. The scutellum is quite concealed. The 
prosternum is very small, the small, conical, front coxee being placed very near the 
front, so that there is only a very short transverse band in front of them ; the 
prosternal process is remarkably small, very acuminate, much compressed, and 
frequently its apex is prolonged so as to form a very slender, elongate, excessively 
