36 



THE FAUNA OF THE DEEP SEA 



In many deep-sea forms the tentacles are consid- 

 erably shorter and the apertures larger than they are 

 in shallow- water forms. It is difficult to believe that 

 such forms, perforated by, comparatively speaking, 

 large holes, could manage to live in rapidly flowing 

 water, for if they did so they would soon be smothered 



- M 



---T 



FIG. 2. Sicyonis crassa. M, mouth ; s, ciliated groove ; T, ten- 

 tacles. Each tentacle is perforated by a single large aperture. 

 (After Hertwig.) 



by the fine mud that composes the floor of all the deep 

 seas. In fact anemones of the type presented by such 

 forms as Sicyonis crassa are only fitted for existence 

 in sluggish or still water. 



Another character that must be taken into con- 



