212 THE LIVING ANIMALS OF THE WORLD 
African species is perhaps the better known of the two. On the approach of the dry season it 
buries itself in the mud at the bottom of the river, and when the latter becomes dry the mud 
hardens, holding the fish a prisoner till the return of the wet season several months later. A 
considerable number of these fishes have from time to time been dug out and sent to England 
enclosed in the mud into which they had retreated. The writer remembers assisting in the 
liberation of some during the last meeting of the British Association at Oxford. So hard haa 
the prison-walls become that the mass had to be plunged into tepid water; this soon brought 
about a dissolut’on of the soil, and in a short time the fishes were swimming about as if in 
their native rivers. The African lung-fish is known also as the MUD-FISH; its American relative 
as the LEPIDOSIREN, or SOUTH AMERICAN Mup-Fisul. In the American species, as in its African 
relative, the fins are whip-like in form; but the hinder or ventral pair, which correspond to 
the hind limbs of the higher vertebrated animals, are remarkable in that in the male they 
develop during the breeding-season numerous thread-like processes, richly supplied with blood, 
the function of which is as yet unknown. 
The young, both of the African and South American mud-fishes, bear external gills closely 
resembling those of the tad- 
poles of the frog and other 
Amphibia; traces of these 
gills remain throughout life 
in the African form. 
—— 2 
CHIMERAS 
Shark-like in their 
general chaiacters, the 
CHIM-ERAS, now briefly con- 
sidered, are nevertheless 
regarded as constituting a 
very distinct group of great 
antiquity. 
i The modern representa- 
BRR DAS. Rugland Sons tives of the group are few in 
BOTTLE-NOSED CHIMARA number — five species in all. 
The remarkable structure in front of the mouth is probably an organ of touch Of these, the species shown in 
the accompanying photo- 
graph and the SEA-CAT are remarkable for the possession of a movable tentacle on the snout. The 
under surface of this tentacle is armed with small spines, and fits into a hollow in the head. 
The first back-fin is supported in front by a strong spine, and can be depressed into a sheath 
in the body-walls. The teeth take the form of large plates closely united with the jaws, and 
studded with hardened points, or “ tritors.”’ 
One species widely distributed in the Mediterranean and Atlantic is taken usually in deep 
water; it is the largest living species, often attaining a yard in length. Its occurrence is, 
however, very erratic, months elapsing without any being taken; at other times several will 
be caught in a few days. A closely allied fish is often exposed for sale in the Lisbon markets, 
where it ranks with the Sharks as a food-fish. 
The egg of the BOrTLE-NOSED CHIM4:RA is perhaps the only egg with a mimetic resemblance 
to a foreign object. It is elliptical in form, and bordered by a fringe, so as to present a close 
resemblance to a piece of seaweed. 
In the next chapter we begin the description of the great group of Fan- and Fringe-finned 
Fishes, which, briefly, embrace all fishes not grouped among the Lung-fishes, Chimeras, or 
Sharks. The anatomical characters used for the purpose of classifying this great group are 
not discussed here, save only in a few cases of prime importance, when features such as can 
readily be observed, without demanding an intimate knowledge of anatomy, are selected. 
