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 antennas, 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 L'un- 

 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- 



