Subclass TELEOSTEI. 



Skeleton osseous. Skull with cranial sutures. Vertebrae com- 

 pletely separated, and the posterior extremity of the vertebral 

 column bony, or having bony plates. Branchiae free, and the 

 water discharged through a single aperture on each side, protected 

 by a bony gill-cover or opercle ; branchiostegal rays present. A 

 non-contractile bulbus arteriosus, having a pair of valves at its 

 commencement. Optic nerves decussating. 



The fishes which compose this subclass form the great bulk of 

 those existing at the present day, and are popularly known as the 

 " true fishes." In geological sequence they appeared subsequently 

 to the Chondropterygii, their first traces being found in the Cre- 

 taceous period towards the close of the Mesozoic epoch. 



Syncqjsis of Orders * amonyst Indian Teleostei. 



All the fin-rays articulated, with the 

 exception of the first in the dor- 

 sal and pectoral which sometimes 

 are more or less ossified. Ven- 

 tral fins, when present, abdomi- 

 nal and spineless. Air-bladder, 

 if existing, having a pneumatic 

 duct (except in Scombresocida>) . 1. PHYSOSTOMI. 



A portion of the dorsal, anal, and 

 ventral fins unarliculated, form- 

 ing spines f. Air-bladder, when 

 present, completely closed in 

 adults, not possessing a pneu- 

 matic duct 2. ACANTHOPTEEYGII. 



All the rays of the vertical and ven- 

 tral fins articulated ; the latter, 

 when present, being jugular and 

 thoracic 3. ANACANTHINL 



* The above Orders are given in accordance with commonly received views 

 or those of Miiller somewhat modified ; but they are of very different values, and 

 must be largely altered when the developmental and general anatomy of fishes 

 becomes better known. 



t There are some genera in which the fins can hardly be said to possess any 

 true spines, aa amongst the Trachinidce, Aulostoma, &c. 



