204 
HISTORY OF BRITISH CRUSTACEA. 
timber, and from other extraneous bodies which might in- 
terfere with respiration. When removed from the water 
and placed upon a resisting surface, the little Crustacean 
bends the abdomen under the thorax, brings the terminal 
appendages between the antennae, and then suddenly resum- 
ing its straight condition, springs to a considerable distance. 
The habits of Chelura terebrans are truly xylophagous, 
and it excavates the timber not merely for the purpose of 
concealment, but with the object of employing it as food, 
which is apparent from the fact that the alimentary canal 
may be found on dissection filled with minutely comminuted 
ligneous matter. It will freely attack a piece of timber 
placed with it in a glass of sea-water, so that its habits may 
be studied in confinement. Timber which has been sub- 
jected to the ravages of Chelura presents a somewhat diffe- 
rent appearance from that which has been attacked by Lim- 
noria terebrans . In the latter, we find narrow cylindrical 
burrows running deep into the interior, while the excava- 
tions of Chelura are considerably larger, and more oblique 
in their direction, so that the surface of the timber, thus un- 
dermined by these destructive animals, is rapidly washed 
away by the action of the sea, and the excavations are ex- 
posed in the greater part of their extent, the wood appear- 
