COLEOPTEROUS INSECTS. 133 
and it is somewhat shining. It is liable to great 
variation in size, some of the specimens which we 
have seen, among an extensive series in the posses- 
sion of James Wilson, Esq. measuring three and a 
fourth inches in length, and an inch and a half across 
the elytra, while others do not exceed two inches 
in length and one in breadth. It is a native of 
Java, and seems to occur in considerable plenty in 
some parts of the country. 
DYTISCIDiE. 
A numerous group of carnivorous beetles, belong- 
ing to the present section, inhabit the waters of 
lakes and ponds, both as larvae and in their perfect 
condition. ' Although frequenting an element so 
different in its nature from that in which other in- 
sects live, there is no very marked difference in 
their structure, a slight modification of certain parts 
sufficing to adapt them to their new abodes. Their 
motions are effected by means of the hinder pair of 
legs, which are rather long and flat, and have the 
tibiae and tarsi densely fringed with long stiff hairs, 
presenting a pretty broad surface to the water. 
Their respiratory apparatus in no respect differs 
from that of other insects ; but, in order to bring the 
stigmatic openings in contact with the air, they are 
obliged from time to time to repair to the surface. 
This is speedily effected merely by stopping the 
movements of the legs; for as the body is specifically 
