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Show 1882.] ANATOMY OF ERETHIZON DORSATUS. 277 of the caecum which is opposite the entrance of the ileum. This band is much more marked on the colon of Hystrix cristata than on that of Erethizon. There is the normal ileo-caecal valve, and besides this a very remarkable valvular constriction, or circular reduplication (c), at the entrance into the large intestine from the caecum. It is something like the pyloric valve, only less defined, especially on one side1. A n essentially similar structure exists in the Guinea-pig, of which I have not met with any description. There is no spiral valve in the caecum, but only a series of constrictions Fig. 6. h.a. V.C. Abdominal aspect of the liver of Erethizon dorsatus. Letters as before; and C, caudate lobe; h.a, hepatic artery; h.d, hepatic duct; p.v, portal vein. corresponding to the sacculi formed by the longitudinal bands. There are no Peyer's patches ; but there is a chain of glands (sixteen, single or in pairs) which extends across from the ileo-caecal valve to the caeco-colic aperture. The liver consists of the normal four large lobes, with a small Spigelian and caudate lobe. There was, however, no gall-bladder in the specimen examined. The right segment is much larger than 1 A preparation showing this structure, made from the specimen here described, has been preserved in the Museum of the Eoyal College of Surgeons. |