154 DARK UNFATHOMED CAVES OF OCEAN 



gorging themselves with the ooze — as earthworms do 

 with garden mold — for the sake of the particles of 

 organic matter that may be mixed with it. Among the 

 starfishes we find several members of the characteristic 

 deep-sea families to which Porcellanaster, Hymenaster, 

 and Freyella belong. Of these Hymenaster is of 

 peculiar interest, because it carries its eggs in a 

 hollow of the back, which hollow is roofed over by a 

 sort of secondary skin so as to form a covered brood- 

 chamber : a hole in the roof, which can be closed at 

 •will, gives exit to the young. Conspicuous among the 

 sea-cucumbers are the species of Deima, curious forms 

 with a strong resemblance to large sea-slugs, and 

 differing from Holothurians of all other families in 

 having the body encased in a firm calcareous shell 

 something like, though not so strong and thick as, 

 that of a sea-urchin. 



Several species of crustaceans, most of which are 

 either blind or have small or defective eyes, crawl or 

 flit over the ooze. The commonest of them seems to 

 be a hermit-crab [Parapagtcrus pilosimamis), whose 

 habit of living in a house of sea-anemones has already 

 been referred to : the eyes of this creature though 

 small, are quite perfect in form and colour, and since 

 there can be no doubt that the animal actually lives 

 upon the bottom at depths to which no sunlight can 

 possibly penetrate, we are almost led to infer that the 

 light by which it sees must emanate from the sea- 



