174 BRITISH FISH AND FISHERIES. 



CHAPTEE VII. 



CARTILAGINOUS FISHES. 



Here we leave the osseous fishes, and pass to 

 the section of cartilaginous fishes, (^Chondrop- 

 terygii,) iu which the skeleton is never thoroughly 

 ossified, but remains permanently as tough car- 

 tilage. 



This class, or great section, contains two 

 orders : — the first, containing such species as 

 have the gills free ; the second, such as have 

 them fixed. 



First order : Gills free. 



In the fishmongers' shops of our metropolis, 

 huge examples of the sturgeon, (^Accipenser 

 sturio,) a fish regarded as royal, is often to be 

 seen. It is, however, only a royal fish when 

 caught in the Thames, within the jurisdiction 

 of the lord mayor, it being by ancient custom 

 reserved for the royal tables. The sturgeon 

 has a long, pointed, conical snout ; the mouth 

 opens underneath in the throat ; the body is 



