350 TOILERS IN THE SEA. 



tenanted tombs of Egypt." l Professor Allman says 

 that " 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 dis- 

 section filled with minutely comminuted ligneous 

 matter. Timber, which has been subject to its 

 ravages, presents a somewhat different appearance 

 from that which has been attacked by Limnoria. In 

 the latter we find narrow cylindrical burrows running 

 deep into the interior, while the excavations of 

 Chelura are considerably larger, and more oblique in 

 their direction, so that the surface is rapidly washed 

 away by the action of the sea." 



We have already quoted the authority of Professor 

 Agassiz for the destructive action of excavators on 

 the old masses of dead coral, and we will again 

 refer to his remarks in this connexion, as they show 

 the extensive character of these operations. " Innu- 

 merable animals," he says, " establish themselves in 

 the lifeless stem, piercing holes in all directions into 

 its interior, like so many augers, dissolving its solid 

 connexion with the ground, and even penetrating 

 far into the living portion of these compact com- 

 munities. The number of these boring animals is 



1 W. Thomson "On Chelura Terebrans? &c., in "Annals 

 Nat. Hist.," vol. xx. (1847), p. 161 ; and Prof. Allman in 

 "Annals Nat. Hist.," vol. xix. (1847), p. 362, with figures. 



