THE SCALES OF THE MORAIYRID FISHES, WITH 

 REMARKS ON ALBULA AND FLOPS 



By T. D. a. COCKERELL 

 University of Colorado, Boulder, Colo. 



The Mormyridse constitute a remarkable family of Malacop- 

 terygian fishes confined to Africa. The brain is of unusual size and 

 the shape of the head is peculiar, in some forms being produced 

 into a long snout, reminding one of an ant-eater. The Nile system is 

 rich in these fishes, having no fewer than seven genera, as follows : 

 Mormyrops (one s])ecies), Petrocephalus (4), Marcusenius (4), 

 Gnathoncmus (5), Monnyrns (4). Hyperopisns (one), and Gym- 

 narchus (one). The last, Gymnarchus niloticus, constitutes a dis- 

 tinct subfamily, having many peculiar characters, in consequence of 

 which Giinther treated it as a distinct family, Gymnarchidae. In 

 Gill's arrangement, published in 1872, the Mormyridse and Gym- 

 narchidge constitute the Scyphophori of Cope, and are thought to be 

 nearest related to the Gymnonoti (Gymnotidae). It is now known, 

 however, that the Gymnotids are really allies of the Characinidae, 

 and consequently little allied to the Mormyrids. According to Bou- 

 lenger, the Mormyridse appear to be nearest to the Albulidae, but it 

 is recognized that the relationship is not at all close. Thanks to the 

 kindness of Doctor Boulenger and the government of Egypt, I have 

 received specimens of five genera of Mormyridse proper and scales 

 of Gymnarchus. These fishes all have scales of the same general 

 type; cycloid with well-developed circuli and with strong basal 

 radii. The truly remarkable feature is found in the apical radii, 

 which are greatly modified and join irregularly, forming a network, 

 as is well shown in the accompanying drawing by Miss Evelyn V. 

 Moore (figure i). The apex of the scale is usually broad and blunt, 

 or even subtruncate, while the base is more pointed and narrower. 



The following key separates the scales examined : 



Scale elongate, much longer than broad i 



Scale not thus elongate 2 



I. Scales near lateral line 7-75 mm. long, about 3.5 broad. Yellowish, sub- 

 opaque, with the circuli extremely fine ; reticulation of radii extend- 

 ing down sides, the spaces often diamond-shaped ; scales of dorsal 

 region much smaller Gymnarchus niloticus 



Smithsonian Miscellaneous Collections. Vol. 56, No. 3 



