286 



COMPARATIVE ANATOMY 



CHAP. 



FIG. 224. Pelagothuria natatrix (after Ludwig), completed ; from above. 1, Body ; 2, anus. 



FIG. 225. Pelagothuria natatrix (after Ludwig) ; front view, i.e. from the oral pole. 1, Mouth ; 

 2, oral tentacles : 3, disc ; 4, canals of the disc. 



