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Show 656 MR. A. S M I T H W O O D W A R D O N T H E SO-CALLED [Nov. 20, Salmonoids, have been assiduously collected since the days of Mantell, and are well represented in many museums ; but nothing of importance with reference to their osteology has been published within the last half-century. It is impossible to make further progress in comprehending the fish-fauna of the Cretaceous period until a detailed study of all the knoAvn skeletons has been accomplished ; and it is the object of the present communication to begin such a review of the materials at present available for discussion. A beginning is made with the so-called Salmonoids of the English Chalk, because these have been the least elucidated by recent discoveries in corresponding strata elseAvhere. The great Sauroid fishes like Portheus and the long-snouted Protosphyrcena have been discovered in perfection in the Chalk of North America, while Enchodus and Dercetis have been found beautifully preserved in Westphalia and the Lebanon; but tolerably complete specimens related to the supposed Salmonoid Osmeroides are known only from the Chalk of Bohemia, and as these exhibit merely natural casts of the actual fossil they are comparatively unsatisfactory for study. The generic name Osmeroides was originally giA^en by Agassiz to some fishes from tbe Cretaceous of Westphalia, regarded by Pictet and the present writer as undoubted Scopeloids. Many examples of these species exhibit very distinctly the characteristic exclusion of the maxilla from the margin of the upper jaw; and they have few, well-spaced branchiostegal rays, without any gular plate. When the same name was afterwards applied to fossils discovered by Dr. Mantell in the English Chalk, it was expressly stated by Agassiz that the determination of generic identity was uncertain and provisional; and tbe following description will demonstrate that the Westphalian and English fishes in question belong even to distinct families. Although Agassiz himself hesitated to distinguish between Salmonoids and Clupeoids when dealing with fossils, preferring to combine them in one family " Haleeidse," subsequent authors appear to have unanimously assigned the English Osmeroides lewesiensis to the Salmonidse. It is thus of much interest to turn to a detailed examination of the knoAvn specimens. 1. OSMEROIDES LEWESIENSIS. (Plate XLII.) Osmeroides lewesiensis, L. Agassiz, Poiss. Foss. vol. v. pt. i. p. 14, pt. ii. p. 105, pi. Ix. b. figs. 1, 2, 5-7 (nee figs. 3, 4), pi. Ix. c. (1834-44) ; A. S. Woodward, Proc. Geol. Assoc, vol. x. p. 322 (1888). Salmo lewesiensis, G. A. Mantell, Foss. South Downs, p. 235, pi. xxxiii. fig. 12, pi. xl. fig. 1 (1822). Osmeroides mantelli, L. Agassiz, Neues Jahrb. f. Mineral. 1839, p. 121 (name only) ; G. A. Mantell, Wonders of Geologv, ed. 3, vol. i. p. 427 (1839). Though many of the smaller features in the skeleton of this fish still remain to be discovered, nearly all its principal characters can noAv be ascertained. The beautiful series of specimens in the |