A MPHIBIANS— FISHES 1 7 1 



great size of their eggs, which appear to undergo the greater part, if not the whole, 

 of their development within the mouth of the female parent, from which receptacle 

 specimens have been taken. This remarkable nursery arrangement is paralleled 

 by a South American frog (Rhinoderma darwini), in which the eggs are hatched 

 in the vocal sacs, or bladders, whence the young frogs appear in a perfect state, 

 having undergone their tadpole stage within the egg. The genus Hylambates, it 

 may be added, together with the allied Cassina, Megcdixcdus, Rappia, and 

 Arthroleptis, is peculiar to Africa, most of the species of these genera coming from 

 the tropical zone, and more especially the west coast. Two other noteworthy 

 Ethiopian amphibians, each representing a genus by itself, are the hairy frog 

 (Trichobatrachus robustus) from the Gabun, and Bates's frog (Campsosteonyx 

 batesi) from the Cameruns. 



Three groups of fresh-water fishes stand out as pre-eminentl}' 

 characteristic of Ethiopian Africa, although, as might be expected, 

 and as already mentioned in Chapter I., a certain number of them enter the North 

 African region. The most absolutely peculiar group, and one which has no living 

 representative in any other part of the world, is that typified by the bichir 

 (Polypterus bichir) of the Nile, and including other species of the same genus, such 

 as P. congicus and P. delhezi from the Congo, as well as a second genus from Old 

 Calabar. These fishes are the sole survivors of an ancient group known as fringe- 

 finned ganoids (Crossopterygii), which take their name from the remarkable 

 structure of the first pair of fins. These consist of a short solid basal lobe from 

 which proceed a number of rays so arranged as to give to the whole fin somewhat 

 the appearance of a fan. The tail is of somewhat similar form ; and the body is 

 clothed in a complete suit of bony armour, consisting of a number of oblique rows 

 of rhomboidal plates, faced with hard, shining enamel. In shape, the bichirs, 

 which grow to a considerable size, are somewhat pike-like fishes, but are specialty 

 characterised by the back-fin being split up into a number of finlets, whence the 

 name Polypterus — many finned. The number and size of these finlets, and the 

 length of the spaces by which they are separated from one another, vary with 

 the species. The reed -fish of Old Calabar and the Niger (Calamoichthys calabaricus) 

 is of a more elongated shape, and is the sole representative of its genus. 



The second peculiar family of Ethiopian fishes is that of the eel-like lung-fishes 

 of the family Lepidosirenidce ; the group is, however, not restricted to Africa, as it 

 has a nearly allied representative in tropical South America, and a second, but less 

 closely related, cousin in Queensland. All these fishes breathe in part by lungs, and 

 in part by gills, and collectively constitute the living survivors of the ancient order 

 of Dipnoi. In the young state the African and South American species have external 

 branching gills. The African genus, of which there appear to be three species, 

 namely, Protopterus annectens of the Gambia, P. ceiliiopicus of the White Nile 

 and the Albert Edward Nyanza, and P. dolli of the Congo, is characterised by the 

 eel-like form of the body, the presence of three tentacles to each gill-opening, and 

 the cylindrical, whiplash-like form of the pectoral and pelvic pairs of fins, which 

 are widely sundered from one another. These fishes grow to very considerable 

 dimensions, and subsist on the frogs, fishes, and insects to be found in the muddy 

 waters in which they dwell. In the dry season they bury themselves in the mud, 



