XXI MALACOPTERYGII pee 
authors. Ninety-three species are known from the fresh waters 
of Africa north of the Tropic of Capricorn, and may be referred 
to two sub-families and ten genera ! :-— 
Gi.) MorMyYRINAE, with teeth on the parasphenoid and tongue, 
with ventral, anal, and caudal fins, and a simple air-bladder ; 
vertebrae 37 to 64; peculiar (Gemmingerian) linear bones, with- 
out known homologues, along each side of the tail, above and 
beneath the electric organ; scapular foramen in the scapula, or 
between the scapula and the coracoid. Mormyrops, Petrocephalus, 
TIsichthys, Marcusenius, Stomatorhinus, Myomyrus, Gnathonemus, 
Genyomyrus, Mormyrus. 
(ii.) GYMNARCHINAE, without teeth on the parasphenoid and 
tongue, without ventral, anal, or caudal fins, and with a cellular 
air-bladder ; vertebrae about 120; Gemmingerian bones absent ; 
scapular foramen in the coracoid. Gymnarchus. 
Fossil Mormyrids are unknown. 
Venerated by the ancient Egyptians, the Mormyrs of the Nile 
are frequently represented on hieroglyphics and mural paintings 
as well as in bronze models. Very little is known of the habits 
of these Fishes. Prof. G. Fritsch, of Berlin, during his stay in 
Eeypt for the purpose of experimenting on electric Fishes, observed 
that they perish very rapidly when removed from the river, and 
he had the greatest difficulty in keeping some alive in an aquarium 
for two or three days. The species with comparatively large 
mouths (Mormyrops, Gymnarchus) feed principally on fishes and 
crustaceans, the others on tiny animals and vegetable and more 
or less decomposed matter. Delhez, on the Congo, found that 
many are attracted to the borders of the river in the neighbour- 
hood of human dwellings, where they feed on the refuse thrown 
into the water. It is probable that the species with a rostrum 
use it to procure small prey hidden between stones or buried 
in the mud, and that the fleshy mental appendage with which 
many are provided is a tactile organ compensating the imperfec- 
tion of the vision in the search for food. A small Mormyrid from 
the Congo (Stomatorhinus microps) has the eyes so much reduced 
and the skin so feebly pigmented as to convey the impression of 
a cave Fish. Until quite recently, absolutely nothing was known 
1 For a general account of the Fishes of this family, cf. Boulenger, P.Z.8. 1898, 
p. 775, and Poissons du Bassin du Congo, p. 49 (1901), where a bibliographical index 
to the principal anatomical and physiological publications will be found. 
