AMPHIBIOUS FISHES. 549 



have received from naturalists the expressive name of Dipnoi, a term 

 formed from two Greek words, meaning animals with twofold respi- 

 ration. 



Two geuera, each comprising only one species, make up this sub- 

 class Dipnoi. Gambia, Zanzibar, Senegal, the region of the White 

 Nile, and the Niger, are the native haunts of the African species, the 

 Protopterus annectens, or anguilliformis / the other species, Lepido- 

 siren paradoxa, is found in the valley of the Amazonas. 



The latter species is but ill represented in collections; there are 

 in Europe only a very few specimens. According to Mr. Bates, the' 

 natives call it zambaki mboya ; this naturalist says that the Lepido- 

 siren has even penetrated to the great lakes in the vicinity of the 

 Tapajos and the Madeira. M. de Castelnau has caught this animal 

 in a marsh on the left bank of the Amazonas, above Villanova, at a 

 place called Caracauca. 



In Lepidosiren the tail is pointed ; the pectoral and ventral fins, 

 which stand far apart, are not long, and consist of a single ray, not 

 divided into sesTments. The general form is that of an eel, with two 

 threads hanging on each side. In color the animal is dark brown- 

 gray, or olive, w r ith round spots of lighter color, about the size of the 

 scales, and indistinct on the head and the middle of the back. The 

 species appears to grow to the length of about one metre. 



The protopterus, or African representative of the group, is olive- 

 green in color, this tint being varied with- a number of irregular 

 brown or blackish spots. The lower portions are violet. The young 

 are marked with fine lines of light color, which cross each other, 

 forming a regular network. The extremity of the tail is tapering. 

 The pectoral and ventral fins are long, and consist of one ray made 

 up of jointed segments. The bones of the skeleton are of a green 

 hue. 



For our first acquaintance with these animals we are indebted to 

 the naturalist Natterer, who, during his visit to Brazil, obtained two 

 specimens, which he placed in the Vienna Museum. For a long time 

 the Protopterus and Lepidosiren were classed with those batrachians 

 in which the tail persists, as in the axolotl. Later they were consid- 

 ered as forming a sort of intermediate class between reptiles and 

 fishes, and as forming the connecting link between the two. At 

 present naturalists class Lepidosiren and Protopterus among fishes. 



The Dipnoi are not the only class of animals that bury themselves 

 in the dried-up mud after the water has been evaporated by the heat 

 of summer. There is another fish that does the same the mud-fish 

 (Amia), which is found in the fresh waters of the United States. The 

 Amia, too, is indisputably a fish. There appears to exist some rela- 

 tion between this animal's mode of life and the cellular structure of 

 its air-bladder. Still, the Amia is not an amphibian, in the strict 

 sense of the term. For, though its air-bladder resembles the lung of 



