MANUAL OF NATURAL HISTORY. 93 



1. SUB-ORDER. — Cartilaginous Ganoid-Fishes 

 (Clioudrostei). 



Skeleton partly cartilaginous ; vertebral column 

 contains a soft chorda instead of vertebral bodies. 



1. Family. — Sturgeons (Acipenseridse). Body co- 



vered with large indurated plates or tuber- 

 cles; mouth beneath, cirrhated; bony jaws 

 perform office of teeth, 



2. Family. — Spoonbill-Sturgeons (Folyodontidse), 



Body without any tubercles or bony plates ; 

 muzzle excessively prolonged into a flat lan- 

 ceolate plate ; * opercula absent. 



2. SUB-ORDER.— Osseous Ganoid-Fishes (Holostei), 



Vertebral column osseous. 



3. Family. — Bichirs (Polypteridse). Body anguil- 



liform, with hard scales; upper jaw not di- 

 vided ; dorsal fin sub-divided into a row of 

 perfect, distinct finlets; gill-membrane cleft; 

 no opercular-gill, or pseudo-branchia ; a blow- 

 ing-hole on each side with an osseous valve ; 

 pectorals pedunculated ; swimming -bladder 

 double. 



4. Family. — Diamond-Fishes* (Lepisosteidse). Head 



and body mailed with thick plates and scales 

 of stony hardness; upper jaw composed of 

 several pieces; gill-membrane undivided, 

 3-rayed; a respiratory opercular -gill and 

 pseudo-branchia; no blowing-hole; anterior 

 margin of fins covered with two rows of 



* Called also " Bony-Pikes." 



