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Show canicula, Galeus cants, and numerous other Selachians; on the contrary, the two regions normally included an angle of at least 120 . In C. squamulosus (and the same was the case in a specimen of C. granulosus which I examined at the British Museum), " the anterior [portion of the stomach] is much the larger, of an elongate form, narrowed towards its posterior extremity; it passes by an abrupt bend into the second reverted portion, which is the narrowest part of the intestinal tract." 11 and hence is quite different from its supposed congener. Since it is impossible within the limits of the present paper to give a comparative account of the anatomy of the gut of Selachians or even Squaliuse, I will content myself with merely further remarking that the conditions both of the two portions of the stomach of C. calceus described above, and of most of the other features of the gut about to be described, differ from those found in all other Squalidse-which is not at all remarkable considering the extraordinary variety of form of the alimentary canal found in this family. The pyloric portion of the stomach of C. calceus ends in a very short and small cul-de-sac, or, in other words, the duodenum or liomologue of the bursa Entiana arises from the side of the pyloric region just before its termination (fig. 3). This duodenum is remarkable in that (as also to some extent in Lcemctrgus borealis, L. rostratus, ana Spinax niger) it is extremely elongated and slender in form, and not abbreviated and globular as in Centrophorus squamulosus, C. granulosus, Scyllium canicula, and indeed most Selachians. It forms, as shown in fig. 3, a lonii slender tube, about twice the length of the cardiac portion of the stomach, and at most one-quarter of the diameter of the pyloric, and with a very small lumen, which pursues a slightly curved course until it joins the large intestine containing the spiral valve at a point situated considerably posterior to the stomach. In C. squamulosus (and C. granulosus), on the other hand, " the spiral valve commences on the level of the posterior extremity of the stomach," 11 as in Scyllium canicula. The large intestine in C. calceus is not very long, being about three-quarters the length of the pyloric portion of the stomach and but slightly exceeding it in diameter at its widest portion. The contained spiral valve commences at the level of the posterior extremity of the pancreatic lobe which is in contact with the large intestine (shortly to be described), and consists of about seventeen or eighteen spiral turns. Running parallel with the two portions of the stomach and duodenum is an enormously elongated bile-duct (associated with arteries and veins for its entire length and with the large hepatic-portal vein for the greater part), which originates in connection with the right lobe of the liver and terminates at the junction of the duodenum with the large spiral-valve intestine, w^hich it enters by a conspicuous aperture on the 1 9 0 6 .J ANATOMY OF CENTROPHORUS CALCEUS. 8 6 9 11 Giinther, ‘ Challenger ' Report on the Deep-Sea Fishes. 1887. |