CRUSTACEANS. 243 



An ovarium^ consisting of about eight wliite capsules, has appeared 

 on the thorax. 



As the preceding animal, the Asellus, feeds exclusively on decaying 

 leaves, so does the sustenance of the Limnoria terebrans seem to be de- 

 rived entirely from the wooden piles which it is destroying. 



Its ravages consist of innumerable channels or galleries, perforating 

 the wood, until its substance is so much reduced as to fall to pieces, or be 

 washed away by the waves. 



Various expedients have been suggested and adopted for counteract- 

 ing the evil, though hitherto without the slightest success ; but one im- 

 portant experiment, and that which should promise most, has been yet 

 overlooked. It is well known that all the insect tribes are most fastidi- 

 ous in the choice of their food. Multitudes are continually perishing 

 when the sustenance most appropriate is unattainable. Therefore, were 

 the Chain Pier, the pillars, abutments, or other parts, constructed of piles 

 or prisms comprising several diiferent species of wood, that alone which 

 was grateful to the animals would be the subject of their attacks. 

 Whence, by allowing a considerable interval, the kind escaping entirely, 

 or the least injured, would be discovered by inspection. 



It is not improbable that the enigma would be solved by a single 

 experiment. 



Plate LXV. 



Fig. 7. Limnoria terebrans, back. 



8. Under surface. 



9. Head. 



10. Head, shewing the eyes and antennae. 



11. One of the antennae more enlarged. 



12. Limb. 



13. Eye. 



14. Chister of ova. 



15. Ovarium more enlarged. 



All the preceding figures are enlarged. 



