PLAGIOSTOMI OK SELACHII: RAYS. 



255 



meaning cartilage. They are also called Plagiostoini, 

 from the fact that their mouth has a peculiar form and 

 position, being placed transversely on the under surface 

 of the head. The word Plagiostomi comes from two 

 Greek words, plagios, oblique, and stoma, a mouth. 

 And they are also often called Elasmobranchii, from two 

 Greek words, elasma, a strap, and bmychia, gills, from 

 the peculiar nature of their gills. Instead of being free on 

 their outer margins, as in all the more common fishes, the 

 gills of these fishes are fixed, that is, they are attached by 

 both margins ; and the gill-openings are without gill-covers. 



FIG. 294. FIG. 295. 



Sting Kay, Trygon hastata, Storer. Thornbaok Ray. 



The fishes of this great group that are known under 

 the name of Rays or Skates or RAIJE, have the body, 

 except in a few species, exceedingly broad and flat, with 



