Page:Jardine Naturalist's library Entomology.djvu/140

134 adhering to the more simple division and nomenclature indicated on a former page. It will be seen, moreover, that two of the parts which we have not regarded as entitled to a separate consideration, the duodenum and the colon, are thought to exist in only a very few species, and even then they are not particularised by any one constant character. The intestine commences immediately behind the chylific ventricle, from which it is separated by an annular constriction or sphincter. This alone points out its origin, when the biliary vessels are placed towards the anus; but being usually inserted immediately beneath the sphincter in question, they then mark precisely its anterior limit. The small intestine, in its ordinary state, is a slender simple tube, very variable in length. In general, it is a good deal shorter than the body, frequently shorter than the chylific ventricle, (as in the Chrysomelidæ,) sometimes it attains the length of the body, and in a few instances exceeds it. In certain cases it deviates from a simple tubular form, and becomes inflated more or less abruptly into a clavate or oval-shaped bag. This is well exemplified in the common cock-chafer, (Plate II. fig. 3 f,) where it forms a large ovoid pouch, and presents, when distended, five projecting ribs, which correspond to a series of imbricated plates in the interior. In this case there is an additional inflation, of much smaller size, a little behind the principal one. "If the name of this