430 



ZOOLOGY. 



native name being " barramundi. " Nothing is known of its 

 breeding habits or mode of development. The eggs when 

 ready to be laid are 2.5 millimetres in diameter. The lower 

 part of the oviduct is much as in Menopoma. Fossil teeth 

 of Ceratodus occur in the Jurassic beds of Wyoming, and two 

 species have been found in still older beds in Illinois, regarded 

 by Cope as either Upper Carboniferous or Permian. Thus, 



Fig. 395. Protopterus annectens, a Lung-fish of Africa. One third natural size. 



as remarked by Gunther, we have in Ceratodus a genus 

 which has survived from the Triassic period. 



The lung-fish are distinguished by two well-formed lungs, 

 and the narrow ribbon-like fins. In Lepidosiren paradoxa 

 Fitzinger, there are five gill-arches, Avith 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 



in, 



337 



Figr. 396. 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 haemal arche-* attached to the notochordal 

 sheath ; As, haemal spines ; in, ih, rays of the caudal fin. After Owen. 



inhabits the rivers of Brazil. This is represented in Africa 

 by the closely allied Protopterus annectens Owen (Figs. 395 

 and 396 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. Gtinther states that numerous examples 



