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Show 1902.] FISHES FROM THE GOLD COAST. 335 E u tro piu s MENTALIS. Eutropius congensis Giintli. Proc. Zool. Soc. 1899, p. 730. Eutropius mentalis Bouleng. Poiss. Congo, 1901, p. 269. A dozen young specimens (5-7 in. long) were collected by Mr. Walker on the R. Offim. I believe them to be the same as a specimen of much larger size from the Prah River which, although it had its fin-spines mutilated, I referred to E. congensis. These young specimens do not quite agree among themselves as regards the comparative length of the barbels, but all have the nasal barbel considerably shorter than the maxillary or outer mandibulary one ; and therefore I hesitate to refer them to Eutropius mandibularis1. The amount of variation in the length of the barbels within the limits of a species, and any change in this character dependent on growth, are quite unknown at present. C h r y s ic h t h y s w a l k e r i . Chrysichthys walkeri Giinth. Proc. Zool. Soc. 1899, p. 720. One specimen, R. Offim. C h r y s ic h t h y s l a g o en s is . (Text-fig. 62, p. 336.) Chrysichthys lagoensis Giinth. Proc. Zool. Soc. 1899, p. 725. One specimen, Nyankoma. This specimen is a male 177 millim. long. It presents a peculiar modification of the integument of the buccal cavity, which I have also observed in other specimens of this genus, in which, however, the excrescences were collapsed and indistinct owing to the less perfect state of preservation. On the palate (text-fig. 62, A) the mucous membrane is raised into two fringed ridges divergent towards the pharynx ; the upper part of the pharynx is occupied by a pair of large, elliptic, soft, cushion-like pads, into which the pharyngeal denticles are sunk, and in front of each of which two long papillae are suspended from the roof of the pharynx. Below (text-fig. 62, B), in the median line between the roots of the anterior branchial arches, a high, short ridge rises, with a fringed flap dependent on each side; finally each branchial arch is provided with two rows of soft papilliform gill-rakers. There are two functions which may be ascribed to this singular structure. It may serve as an organ of taste by which the fish is able to distinguish in muddy water between nutritive and uneatable substances : or, as many Cat-fishes carry their ova and young in the mouth, it may assist in the lodgment or, perhaps, 1 Unfortunately I am unable to re-examine the type of E. mandibular is. The majority of the specimens described in the paper quoted were lent to me for description bv my friend, the late Mr. T. Moore, Curator of the Free Public Museum, Liverpool with the understanding that all unique types should be returned to him. This was done, and the safe arrival of the specimens acknowledged by him. However, none of them can now be found by Mr. Moore's successor, Dr. J. 0 . Forbes, who, at my request, kindly instituted a search for them, |