CHUSTACEA. 515 



Genus, Aselius. — Geoffrmj. 



Body long, oval, like Janira. First antenuEe short, second 

 long. First pair of legs with hands, all the rest pediform, 

 slender. 



AsELLUs AQUATiCTJS. — LinncBus, Syst. Nat., ii, 1061, — Bate and 

 Westwwod, p. 343. 

 Common in freshwater ponds and ditches throughout the 

 kingdom. 



Genus, Limnoeia. — Leach. 



Like Asellus, but with shorter segments to the body. Posterior 

 portion divided into six segments. 



LiMNORiA LiGNORUM. (The Gribble). — Ratlike, Shriht. of Natur. 

 SeM., vol. 101, t. 3,/. 14 (1799).— Bate and IVestwood, p 351 , 



All round ouv coast, in submarine timber, which it eats with 

 avidity. The bores are one fifteenth of an inch in diameter. 

 Admiral Sir W. Drummond, when Superintendent of H.M. Dock- 

 yard, Devonport, afforded me every facility to examine the 

 submerged timber in the arsenal and Sound. Assisted by the 

 extensive knowledge and experience of Mr. Moore, the master 

 shipwright of the yard, I was by comparison of dates, according to 

 the length of time that the timber was submerged, able to arrive 

 at a general conclusion that these animals destroyed the sunken 

 wood at the average rate of one quarter to half an inch in depth 

 a year. The earlier years were scarcely as much, but that with time 

 the rate increased, so that a five inch solid balk of timber would be 

 eaten up in about ten years. They seemed to attack all timbers 

 equally, but the knots resisted their depredation, and the most 

 successful of artificial means was the rust that penetrated the 

 wood from the presence of nails and bolts of iron. 



ARCTUEID^. 



Genus, Aectuhus. — Latrielle.- 



Body long. First antennee short ; second antenuEe long. Four 

 anterior legs filiform. Three posterior pediform. 



Aectueus longicoknis. — Sowerhy, Brit. Miscel., t. 19. — Bate and 

 Westwood, p. o65. 



