806 INSECTA. . 
seizing their prey, and are termed raptor. Others have the tarsi com- 
pressed and ciliated or even hairy, demonstrating their aptitude to be used 
as oars, or for swimming, and these are called natatorii. In the family of 
bees, the legs and the first joint of the tarsi are formed in such a manner 
as to brush off and carry away the pollen or dust from the stamina of flowers, 
and the tarsi and anterior legs in other species are sometimes broad, fur- 
nished with dentations or small spines, and calculated for digging in the 
earth (pedes fossorii.) These feet also in some are not subservient tc mo- 
tion, as in many Papilionides, and they differ in others according to the sexes, 
The abdomen, forming the third and last part of the body, includes the 
viscera and the sexual organs. It is composed of from six to nine seg- 
ments, each divided into two semicircles or plates united laterally, the 
under portion being termed the belly. The organs of generation are situ- 
ated at the posterior extremity; and hooks or forceps of different forms 
accompany these parts in the male. The oviduct of many females is pro- 
longed beyond the termination of the abdomen, sometimes in form of an 
articulated tube; sometimes as an ovipositor or auger (terebra,) composed of 
plates or filaments often dentated at the end. This oviduct terminates in a 
sting (aculeus) in the females and neuters of many hymenoptera. The exte- 
rior envelope of insects, which is more or less solid, serves the double pur- 
pose of outward protection and internal support. Less complicated than 
the skin of higher classes, it seems to consist of but two layers, the epidermis 
or outer skin, and the mucous tissue. Detached from the mucous tissue, the 
epidermis of insects is almost pellucid, or semi-transparent, and colorless. 
From its manner of growth, and the great proportion of gelatine in its com- 
position, the substance of the outer envelope is of a horny consistence, more 
flexible than the coverings of the crustacea, when the phosphate of lime pre- 
dominates over the animal matter. : 
The body of a caterpillar, deprived of the epidermis, presents the same 
colors as before; and it is conceived that the growth of the epidermis, being 
stopped by the layers which grow successively below, destroy the functions 
of the envelope, and occasion the change of covering observed to take place 
in the animals at this stage. The appendages of the skin consist of spines,‘ 
hairs, and scales; the first two being merely prolongations of the epidermis. 
The solid soft parts of insects are of two kinds. The first, termed muscles, 
are formed of soft fibres, disposed in bundles, capable of producing motion 
by their contraction in the parts to which they are affixed. These muscles 
are always attached to the harder parts by a tendon of a horny consistence. 
The other soft parts, formed also of muscular fibre, constitute the interior 
organs, which, with the fluids, perform the necessary functions of vitality. 
There are generally two muscles concerned in the motion of each part. 
The muscles which move the head are situate within the thorax, and the 
principal ones serve to raise or lower it. Within the thorax likewise are 
placed the muscles whicn move the wings and feet; and besides these are 
