458 GEOGRAPHICAL ZOOLOGY. [part iv. 



Sub-class II.— DIPNOI. 



Family 92. — Sirenoidei. (3 Genera, 3 Species.) 



" Eel-shaped fresh-water fishes, covered with cycloid scales ; 

 the vertical fins forming a continuous border to the compressed 

 tapering tail." 



DiSTEiBUTiON. — Eivers of Tropical Africa, South America, and 

 Australia. 



The genera are : — Protoptcrus (1 sp.), Tropical Africa ; Lcpido- 

 sircn (1 sp.), Amazon Valley ; Ccmtodus (1 sp.), Queensland. 



Sub-class III.— GANOIDEI. 



Order I.—HOLOSTEI. 

 " Body covered with scales." 



Family 93.— AMIID^. (1 Genus, 1 Species.) 

 " A fresh-water fish, with cycloid scales and a long soft dorsal 



fiD." 



DiSTEiBUTiON. — United States. 



Family 94.— POLYPTEEID^E. (2 Genera, 2 Species.) 



" Fresh- water fishes, with ganoid scales and dorsal spines." 



Distribution. — Central and Western Africa. 



The genera are : — 



Polypterus (1 sp.), the Nile and rivers of West Africa; Cala- 

 moichthys (1 sp.), Old Calabar. 



