Fishes from the Cameroon. 43 
as long as deep. Scales 27-28 ,~, 1; lat. lin. sup. 17-20; 
lat. lin. inf. 12-13. Peritoneum black. 
The coloration appears to have been rather dark, but more 
or less so in different specimens. It seems, however, probable 
that the back and upper parts have been blackish, perhaps 
bluish black. In the specimens J take to be males the lower 
jaw, branchiostegal and jugular portions, ventrals and anal, 
as well as the tract between those fins, seems to have been 
(bluish) black. In those which I think are females the 
jugular portion appears to have been orange, the ventrals 
being not black, but only dusky, and only the basal half of 
the anal being black. ‘he pectorals seem to have been light- 
coloured in all specimens. The upper end of the hind 
margin of the opercle is bordered with black in all specimens. 
The number of specimens is eight, and their length (with 
caudal) varies between 180 and 200 millim. 
The dentition of all these specimens is perfectly identical 
and of the same type as that of the fish from Lake Tan- 
ganyika on which Boulenger established the genus G'ephyro- 
chromis*, When examined with the aid of the keys elabo- 
rated by Boulenger +, the fish from the Elephant Lake must 
be referred to the genus Gephyrochromis. It happens, how- 
ever, now and then that members of the genus Tvlapia vary 
with regard to their dentition in such a way that they exhibit 
an outer series of simple conical teeth. Sauvage has remarked 
this about 7. Desfontainest, Lacép., and in his valuable book 
on the Congo fishes Boulenger+ observes concerning 7’. micro- 
lepis (also from Lake Tanganyika) that the lateral cusp of 
the enlarged anterior teeth is very small and sometimes 
absent. Certain specimens even approached FParatilapia so 
nearly “that they could have been referred to that genus, if 
one did not know that their teeth were bicuspid in a more 
youthful stage.” A similar change may take place during 
the development and growth of this species as well, because, 
although in all specimens on hand the outer teeth have the 
same general shape, there may on some few of these teeth 
of the youngest specimen be found some slight traces of a 
lateral cusp. In these circumstances the characteristic that 
should distinguish Gephyrochromis from Tilapia loses con- 
siderably in importance, and it seems almost necessary to 
withdraw the genus Gephyrochromis unless other characters 
besides the dentition are found to separate it from Tilapia. 
Mr. G. A. Boulenger has kindly told me that he is of 
* Ann. & Mag. Nat. Hist. ser. 7, vol. vii.; Trans, Zool. Soc, London, 
yol. xvi. pt. 3, p. 156, pl. xx. 
+ ‘Poissons du Congo,’ Bruxelles, 1901. 
