1902.] FISHES FROM THE GOLD COAST. 335 



EUTRGPIUS MENTALIS. 



Eutropius congensis Glinth. 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. con- 

 gensis. These young specimens do not quite agree among them- 

 selves 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 Eutrop>ius mandibular is ^. 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. 



Chrystchthys walkeri. 



Ghrysichthys ivalkeri Giinth. Proc. Zool. Soc. 1899, p. 720. 



One specimen, R. Offim. 



Ghrysichthys lagoensis. (Text-fig. 62, p. 336.) 



Chrysichthys lagoensis GUnth. 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 papilla are suspended fi'om the i-oof of 

 the pharynx. Below (text-fig. 62, B), in the median line between 

 the roots of the anterior branchial arches, a high, shoi-t ridge i-ises, 

 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 JS. mandihularis. The 

 majority of the specimens described in the paper quoted were lent to me for descrip- 

 tion by 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 b3' him. How- 

 ever, none of them can now be found bj' Mr. Moore's successor, Dr. J. 0. Forbes, 

 who, at my request, kindly instituted a search for them, 



