COMMON HKAllT-TTUCniN. 



193 



is requested to the young state, as, if the peculiar shape of 

 the sub-anal impression be constant throughout its life, and 

 not an effect of abnormal growth, the form must be con- 

 sidered specifically distinct. 



M. Sars has observed Pedicellarice on this species. He 

 says they are but few, from thirty to forty in number. 

 In size they are rather large. They have a short thin 

 stem, and a very large head, consisting of three, dark brown, 

 thick, blunt teeth, which often open and shut as in the 

 other kinds. They stand in five incomplete rows, rather 

 irregularly, and only on the back of the shell. The dark 

 brown head makes them apparent. 



When any of the Spatangi tribe are opened, we find 

 their intestines filled with sand or mud. They seem to 

 swallow those substances for the sake of the animal matter 

 mixed up with them. 



