DISTRIBUTION OF ORGANISMS. 



173 



live in the excavations of littoral rocks, in the hollows of 

 sponges, in the interstices of the radicles of thalassiophytes, 



FIG. 88. 



FIG. 89. 



1 



lulus. 



Scolopcndra. 



under stones, and in general in all bodies which present fissures 



more or less profound They all appear to feed upon 



animal substances M. Bosc tells us they live upon 



polypi and small worms, on which they throw themselves, by 

 darting the anterior part of their body, which they have first 

 contracted." 



The next articulate class demanding attention is the Crus- 

 tacea, animals in which the annular sections are covered with a 

 calcareous shell, and provided with jointed limbs, the respira- 

 tory apparatus being branchial ; all are aquatic, except some of 

 the higher genera, which occasionally adventure upon the land. 

 They are in two great groups, Entoinostraca and Malacostraca, 



