GEOGRAPHICAL ZOOLOGY. 
[part IV. 
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Sub-class II.— DIPNOI. 
Family 92. — Sirenoidei. (3 Genera, 3 Species.) 
“ Eel-sliaped fresh-water fishes, covered with cycloid scales ; 
the vertical fins forming a continuous border to the compressed 
tapering tail.” 
Distribution. — Eivers of Tropical Africa, South America, and 
Australia. 
The genera are : — Protopterus (1 sp.), Tropical Africa ; Lepido- 
siren (1 sp.), Amazon Valley ; Ceratodus (1 sp.), Queensland. 
Sub-class III.— GANOIDEI. 
Order I.—HOLOSTEL 
** Body covered with scales.” 
Family 93. — AMIIDiE. (1 Genus, 1 Species.) 
“ A fresh-water fish, with cycloid scales and a long soft dorsal 
fin.” 
Distribution. — United States. 
Family 94.— POLYPTEKID^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,* Cola- 
moichthys (1 sp.), Old Calabar. 
