144 
CLASS CRUSTACEA. 
pour into the intestine near the pylorus. The alimentary 
canal is short and straight. The sides present a range of holes, 
placed immediately at the insertion of the gills, but which are 
not discovered until these organs are removed. The breast- 
piece, seen internally, presents, at least in many large species, 
some transverse lodges formed by crustaceous laminae, and 
separated in their middle by a longitudinal crest of the same 
consistence. 
The sexual organs of the males are situated near the origin 
of the two posterior feet. Two articulated pieces, of solid 
consistence, in the form of horns, of stylets, or of setaceous 
antenna?, placed at the junction of the tail and thorax, and 
replacing the first pair of sub- caudal appendages, are re- 
garded as the generative organs of the males, or at least their 
sheaths. But according to our observations on various de- 
capods, they should consist each of a small membranaceous 
body, sometimes in the form of a bristle, sometimes filiform, or 
cylindrical, issuing from a hole situated at the articulation of 
the haunch of the two posterior feet, with the breast-piece. 
The two vulva? are placed on this piece, between those of the 
third pair, or at their first articulation, dispositions which 
depend on the enlargement or diminution of the breast-piece. 
Copulation takes place belly to belly. The growth of these 
animals is slow, and they live a long time. It is among them 
that the largest species are found, and those that are most 
useful to us as an article of food ; but their flesh is difficult of 
digestion. The body of some decapods attains a length ex- 
ceeding three English feet. Their forceps, as is well known, 
is very formidable, and so powerful in some large individuals 
as to raise and trip up a goat. They remain habitually in the 
water, but do not perish directly on being exposed to the air. 
Some species even pass a portion of their lives in this latter 
element, and visit the water only during the season of their 
amours, and for the purpose of depositing their eggs. They 
