THE FEATHER CRAB 273 



Richardina, a species of which Dr Anderson found 

 imprisoned in a glass-rope sponge [Hyalonema masoni, 

 F. E. Schulze) dredged in the Andaman Sea at a 

 depth of 498 fathoms ; and Iconaxiopsis laccadivensis 

 (Fig. 66), which has been found lurking in the branches 

 of that strange armour-plated deep-sea zoophyte Calyp- 

 terimts allmani, 



A curious modification of legs, apparently due to 

 the peculiarities of its habitat, is shown by a crab, 

 Ptenoplax notoptts (Fig. 55), which lives in the Bay 

 of Bengal in 100-250 fathoms, in certain places where 

 the bottom consists of a very soft and very copious 

 silt. In this little creature the legs are thickly fringed 

 along both edges, so that the last pair, which are 

 carried obliquely behind the body, are more like 

 feathers than legs, the probable object being to give 

 a light but extensive support, on the principle of the 

 snow-shoe, so as to keep the body from sinking too 

 far into the soft ooze. 



Many good instances of commensalism have been 

 observed among the deep-sea Crustacea collected by 

 the Investigator. That of Chlmiopagttrus andersoni 

 (Fig. 2), a hermit-crab from 102 fathoms off the 

 Malabar Coast, which is protected by a blanket of 

 sea-anemones instead of by an ordinary mollusk shell, 

 has already been sufficiently noticed. Another well- 

 known hermit, found in deep water all the world over, 



is Parapagurus pilosimanus (Fig. 67), which at an 



s 



