CRABS, ETC. 89 
Fic. 99.—Marine cray-fish (Palinurus vulgaris), about } natural size. 
NotE.—On the Florida reef nearly every coral head or branch 
affords protection to one or more cray-fishes, as they are there called. 
The animals partly undermine them, thus serving the coral by pre- 
venting the fatal inroads of sand and mud. 
