XX] 



BATOIDEI 



469 



representatives of which are common in the Coal Measures. In it 

 the snout is reduced so that the mouth is thrust forward and 

 the jaw is attached to the skull in front of the orbit. The teeth 

 are flat and pavement-like and adapted for crushing the Molluscs 

 on which the animal feeds. 



B 



FIG. 229. Rala maculata. From Day. 



A. Dorsal surface, showing the spiracles just behind the eyes. Eeduced. 



B. View of mouth and olfactory pits. 



The BATOIDEI or Rays are, as we have said, ground feeders. All 

 have the true gill openings on the underside of the body : the 

 spiracle alone opens on the dorsal side and is enlarged. It has 



