464 ZOOLOGY. 
in the Jurassic beds of Wyoming, and two species haze been 
found in still older beds in Illinois, regarded by Cope as 
either Upper Carboniferous or Permian. Thus, as remarked 
by Giinther, we have in Ceratodus a genus which has sur- 
vived from the Triassic period.* 
The lung-fish are distinguished by two well-formed lungs, 
and the narrow ribbon-like fins. In Lepidosiren paradozxa 
Fitzinger, there are five gill-arches, with four slits, and the 
body is rather longer, more eel-like, with a blunter snout 
than in Protopterus. It grows to one metre in length, and 
Fig, 422.—Skeleton of Protopterus annectens, showing the protocercal tail and the 
simple rod-like limbs, the pelvic and shoulder girdles, and the nature of the jaws. 
ch, notochord ; p, bones representing the hemal arches attached to the notochordal 
sheath ; As, heemal spines ; in, 2h, rays of the caudal fin.—After Owen. 
inhabits the rivers of Brazil. This is represented in Africa 
by the closely allied Protoplerus annectens Owen (Figs. 421 
and 422 skeleton), which has six gill-arches, with three 
pairs of external gills in the young. It is 40-70 centimetres 
in length. It lives on leaves in the White Nile, Quilimani, 
Niger, Gambia, and their tributaries. It buries itself in the 
mud a foot deep. 
\ V . 
Crass VE—Batracata (Salamanders, Toads, and Frogs). 
General Characters of Batrachians.—We have had an- 
ticipations of the Batrachians or Amphibia in the Ganoids, 
especially the Dipnoan fishes, which it will be remembered 
approach. the members of the present class in the lung-like 
nature of the air-bladder and in the presence of external 
* Description of Ceratodus, Phil. Trans. Roy. Soc., London, 1871. 
Ayer’s Beitriége zur Anatomie u. Phys. der Dipnoér. Jena, 1885. 
