The stomach of the hamster (Cricetus, Cuv.) approximates the common type de scribed above, the stomach being divided into tvvo pouches, separated by a deep constric tion ; the left pouch is cylindrical, the right globular. The cardiac orifice is situated in the former to the right of its base, opening on the constriction itself, so that aliments can pass immediately into the second compart ment by the assistance of a fold, which is pro longed from the cardia into this cavity ; and the pyloric portion may be distinguished, which is more muscular than the rest, and ter ininates in the intestine by a slightly pro minent pylorus.
The Cape mole (Bathiergus, Iliger) like wise conforms to the preceding type of struc ture ; the left compartment of the stomach is of enormous size, elongated and pierced at its base by the cardiac orifice ; the left com partment is of smaller dimensions, of a glo bular form, and separated from the preceding, both by an external constriction and an in ternal fold of the mucous membrane. There are, moreover, two additional folds nearer to the pylorus, which seem to form a third compartment. The orycteres of the Downs (Bathiergus maritimus) has its stomach slightly different ; its position is more longitudinal, so that the left compartment is anterior, and the right posterior ; the pyloric portion short, cylindrical, and directed forwards.
In the beaver (Castor) the stomach is transverse and elongated in that direction, the right portion being larger than that which is situated to the left of the cardia ; the oesophagus is inserted into the first third of its anterior margin by a narrow opening, sur rounded with pointed processes, which are analogous to the fringes formed by the epi dermis in many other Rodents. At the point where it terminates around the opening of the first compartment of the stomach into the second, numerous largely developed culs-de sac are distinguishable, which project more or less beyond the cardia in different individuals. On the right of this orifice commences the pyloric portion, the termination of which is indicated by an external constriction, and by an internal thickened ring. The pylorus is approximated very closely to the cardiac orifice. This pyloric portion, which is more muscular than the rest, is sometimes dilated into a distinct pouch, separated by a con striction from the pyloric cul-de-sac. The internal membrane presents every where the same appearance, except that in the pyloric portion it appears to be more smooth, and its folds take a different direction. On the right of the cardia there is a very thick fold, sepa rating the left from the right compartment.
In the rabbit and the hare (Lepus, Lin.) the stomach is very much elongated, par ticularly in that portion which is situated to the right of the cardiac orifice. This latter portion forms a bulb, the muscular wall of which is thicker than elsewhere, especially in the vicinity of the pylorus, where it is swollen into a muscular ring. In the other parts of the stomach the existence of this layer is scarcely perceptible.
In the lagom) s (Cuv.) we have again the common type of structure, as also in the agoutis and the pacas.
In the pteromys (F. Cuv.) the stomach is situated more transversely, and the two culs de-sac are more distinct ; the right compart ment is the largest, and gives off at an angle a short conical pyloric portion.
In the sciuropteres (F. Cuv.) the stomach is round, deep from before to behind, and having the bottom of the cardiac culs-de-sac formed into a little pouch, and extending slightly beyond the cardia ; the pyloric portion is conical, very muscular, and lined internally with a yellowish mucous membrane, whilst the lining membane of the rest of the stomach is white and arranged in folds, which form arches parallel to the curvatures of the viscus. There are two other folds running longi tudinally on the right and on the left of the cardia, but which probably do not exist when the stomach is distended : these would seem to indicate traces of a division of the cavity into three pouches.
In the dormice (112yoxits, Gm.) the stomach differs in shape in accordance with the appe tites of the different species. In the common dormouse (.111us Gila, Lin.) it is conical, with a small pyloric portion directed forwards ; its membranes are thick and muscular, approxi mating the type of a carnivorous stornach. InlIfyoxusNitela, on the contrary, it is globular, and consists of a single sac; the crypts, the orifices of which open into the cavity of the stomach, form a thick disc in the vicinity of the eardia : these crypts are evidently small culs-de-sac, formed by the mucous membrane and the cellular layer beneath it, which here appear folded upon themselves in irregular festoons, when a section of this glandular disc is examined. The ligneous substances upon which the beavers feed have rendered neces sary this superabundance of the secretions furnished by this gland. A constriction se parates the pyloric portion front the re mainder of the straight part of the stomach. The pylorus consists of a prominent ring projecting into the intestine.