324 



Subclass III. GANOIDEI. 



Fishes with the skeleton more or less ossified. 

 Bulb of the aorta muscular, with numerous valves. 

 Branchiae free ; gill-cavity protected by a gill-cover. 

 Intestine with a spiral valve. Optic nerves not de- 

 cussating. V<^ntral fins abdominal, if present. 



Cfr. MiiUer, Abhandl. Ak. Wiss. Berlin, 1S44, p. 141. 



Synojjsis of the Families. 



I. HOLOSTEI. Body covered with scales ; skeleton bony. 



A. Scales cycloid 1. Aniiidse, p. 324. 



B. Scales ganoid. 



a. Fins without fulcra 2. Polypteridae, p. 326. 



h. Fins with fulcra 3. Lepidosteidae, p. 328. 



II. CHONDROSTEI. Skin naked, or with osseous bucklers. 



Skeleton partly cartUagiaous. 



A. Mouth small, transverse, inferior. 1. Acipenseridae, p. 332. 



B. Mouth lateral, very wide 2. Polyodontidse, p. 346. 



Order I. HOLOSTEI. 



Skeleton bony ; body covered with scales. 



Holostei, Miiller, Abhandl. Ak. Wiss. Berlin, 1844, p. 147. 

 Lepidoganoidei (part.), Owen, Conipar. Anat. of Verkbr. i. p. 12. 



Freshwater fishes of North America and Africa. 



Fam. I. AMUBM. 



Scales cycloid ; a long soft dorsal fin. Abdominal 

 and caudal parts of the vertebral column subcqual in 

 extent. Pseudobranchise none. 



Fresh waters of North America. 

 One genus only. 



