512 FISHES CHAP. 
the great African continent, ranging from the river Senegal and the 
White Nile on the north to the Congo basin, Lake Tanganyika, and 
the Zambesi on the south. Three species are known, P. annectens 
(Fig. 304), P. aethiopicus, and P. dolloi. Protopterus' is usually 
found in marshes in the vicinity of rivers. Voracious in its habits 
the Fish is mainly carnivorous, subsisting principally on Frogs, 
worms, insects, and crustaceans. It is by no means averse to 
preying upon its own kind, and if several of these Fishes are 
confined in the same aquarium they are apt to give free vent 
to their cannibal instincts by biting off the tails or limbs of their 
fellows. The missing parts are soon regenerated, but the new 
members are usually somewhat abnormal, the tail, for imstance, 
never regaining its original length, while a new pectoral limb 
Lepidosiren. Protopterus. Neoceratodus 
Frc, 306.—Map showing the distribution of the surviving Dipneusti. 
may be bifid or even trifid.? The tail is the principal organ 
of locomotion, and by its means the Fish is capable of remarkably 
quick, agile movements. When slowly moving over the bottom 
of an aquarium the paired limbs are observed to move to and 
fro on opposite sides alternately in a somewhat bipedal fashion. 
The limbs are useless for swimming, although it is possible that 
they may be helpful in creeping over the bottom, or in balancing, 
or as tactile organs. Protopterus is said to breathe by its lungs 
as well as by its gills, and to rise to the surface at short intervals 
to take in fresh air. In the dry seasons the marshes in which 
Protopterus lives become dried .up, and to meet this adverse 
1 For a list of the more important papers on Protopterus, see Boulenger, Les 
Poissons du Bassin du Congo, Bruxelles, 1901, pp. 40-42. 
? Traquair, Rep. Brit. Ass. 1871 (2), p. 143 ; Boulenger, P.Z.S. 1891, p, 147. 
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