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Show 1897.] ANATOMY OF A MANATEE. 49 Of the alimentary viscera I have had a drawing prepared of the tongue (fig. 2, p. 48), which does not greatly differ from that of the more common American species. It appears to me, however, that the large patch of circumvallate papillae (Mayer's organ) of the two sides of the tongue are a little more closely approximated than in M. latirostrls. The stomach of Manatus Inunguis shows a few minute differences from that of M. latirostrls. The largest compartment of the stomach is much smoother inside than in either of the two if. latirostrls that I examined; in the smaller spirit-preserved specimen of the latter species, indeed, the wrinkling of the sides of the stomach near to its orifice into compartment IV. was so marked as to suggest the ruminant reticulum. The two lateral diverticula of the stomach are subequal in M. latirostrls, at least in the larger of the two specimens that I examined and in the individuals described by Murie. But in the small M. latirostrls and in M. inunguis the left is considerably the larger ; moreover, this diverticulum is more coiled in the larger M. latirostrls than in either the small specimen or in M. Inunguis--a further difference which may perhaps be due to age. The unpaired glandular diverticulum of the cardiac stomach is relatively shorter in the large M. latirostrls. The bile-duct and the pancreatic duct open on to prominent papillae whose relative positions may be a mark of specific distinction. In M. latirostrls they are rather further apart, and the pancreatic duct is more in front of the orifice of the ductus choledochus than in M. Inunguis, where the latter is behind but markedly below the former. As to the intestinal canal, the most remarkable feature is the great length of the large intestine, which is not far short of the small intestine ; Peyer's patches are numerous, and in the last foot of the ileum I counted twelve of them varying much in shape and size, but being usually elongated and running in the furrows between the rugae of the gut, as indeed Dr. Murie has noted in Manatus latirostrls. At the actual orifice of the intestine into the caecum a patch of exceptional size is found. The general shape of the caecum, which is displayed in the accompanying drawing (fig. 3, p. 50), is precisely like that of the other species of Manatee, and I should not have had the drawing prepared were it not for a peculiar fold of mesentery which it is the main purpose of that sketch to illustrate. This fold, which is not referred to by Dr. Murie, lies on either side of the mesentery supporting the ileum and runs nearly to the caecum. It does not bear a blood-vessel, and the fold of either side is continuous with its fellow by a complete bridge over the front side of the ileum as is indicated in the sketch. Both species are precisely alike in the presence and in the relations of these two mesenteries. On cutting open the caecum it seemed to m e that there was a recognizable difference between the two species. The two orifices of the finger-like appendages of the caecum were closer together in M. latirostrls and to the orifice of PROC. ZOOL. Soc-1897, No. IV. 4 |