Elasmobranchii

Scientific name : Elasmobranchii

This subclass holds all those cartilagineous fish other than chimaeras.
The main features of the members of this subclass, other than a completely cartilagineous fish (a common feature among the Chondrichthyes), are the absence of a gas bladder, a variable number of gills (usually ranging from 5 to 7 among all the species) and multiple teeth rows.
The Elasmobranchii subclass holds sharks, rays, stingrays and sawfishes.