CLASS I. INSEGTA: OKDER 1. COLEOPTERA. 
545 
DYTICUS MARGINALIS. 
A, larva; B, perfect insect. 
DTTICUS JIARGINAMS, FEMALE 
large size. An amusing Frencli writer remarks that, if the common European species — there 
being several kinds — may be considered as provided with muskets, these seem, comparatively, 
to possess cannon. 
THE HYDRADELPHAGA. 
This term is from the Greek hudor, water, and adelphagos, voracious ; the animals which it 
characterizes are pre-eminently carnivorous and rapa- 
cious in their habits. They have a somewhat flat- 
tened oval body, and the legs, especially the hinder 
pair, compressed and fringed with bristles, so as to 
become powerful paddles. Many of these insects are 
of considerable size, the Dyticus marginalis, a Euro- 
pean species very common in ponds, attaining a length 
of more than an inch ; while other species are much 
larger. The larva is of an elongated form, tapering 
toward the tail, which bears a pair of tubular ciliated 
appendages, which the creature applies to the surface of the water to obtain a supply of air for 
its respiration. It is as predaceous as its parent, 
seizing upon other aquatic larvfe with its long- 
curved mandibles, and quickly sucking the juices 
out of the body of its victim. When about to 
change to the pupa state, the larva burrows into 
the bank of its native pond, and there undergoes its 
transformations. 
Harris's Dytice, D. Harrisii, one inch long, 
is common in ponds wdth a clear, sandy bottom, in 
this country. 
The well-known Gyrini, or Whirligigs— MHIq black beetles, which may be seen describing 
circles upon the surface of any piece of smooth water— are also placed in this tribe, although their 
claim to such position is rather doubtful. The European species, Gyrinus natator^ is one fourth 
of an inch long, oval-shaped, of a blackish-brown color ; this may serve as an example of the 
family. 
THE BRACHELYTRA. 
This term is from the Greek brachus, short, and elytron, a case, and refers to the shortness of 
the elytra, which leave a considerable portion of 
the abdomen of these insects uncovered. The 
wings, however, are usually ample, and the crea- 
tures fly well. They are generally of an elongated 
form, and the abdomen, w^hich is horny on both 
surfaces, possesses great mobility. It assists in 
tucking the wings under the elytra after flight, 
and the insects generally raise it when alarmed or 
angry. This attitude has obtained for one Euro- 
pean species, the Goerius olens, the appropriate 
name of Cocktails. The derivation of their other 
vulgar denomination, JDeviVs Coach-Horses, is not 
so clear. The larvae are very similar to the perfect insects, both in appearance and habits. 
Many of them feed in carrion ; others in rotten wood and other decaying vegetable matter. The 
number of joints in the tarsi varies greatly, but five is the prevalent number. 
THE PHILHYDRIDA. 
This term is from the Greek ^^^zYeo, to love, and hudor, water, and is appHed to this small tribe 
from their generally aquatic habits. Most of them Hve constantly in the water, and their legs 
are generally more or less flattened, to render them efiicient as natatory organs. One of the 
Vol. II.— 69 
COCKTAILS. 
