CHELURA TEREBANS. 505 



dilated peduncle which is as broad as long, and fur- 

 nished upon the inner margin with two hooked spines 

 and a few plumose cilia. The antepenultimate pair of 

 caudal appendages have the peduncle long and narrow ; 

 the branches are short : the penultimate pair have the 

 peduncle developed into a large thin plate, produced 

 upon its inner margin to a breadth quite equal to its 

 length ; the branches are short, equal in length, the 

 inner one being not quite so broad as the outer : the 

 ultimate pair have the peduncle very short, but as if 

 to compensate, the branch is greatly developed, being 

 about the length of the inferior antennae, and is very 

 broad, especially near the base, and flattened. The 

 middle tail-piece is of the form of a broad lance-head, 

 attached to the animal by a short foot-stalk. 



This species is one of our most injurious xylophagous 

 Crustaceans. It is commonly found associated with Lim- 

 noria lignorum, but, fortunately for piles and other marine 

 woodwork, it is not so prolific as that species. Its 

 excavations, are, however, much larger and more rapidly 

 executed. It is in fact so destructive that it will destroy 

 a piece of Memel timber thirteen inches square in less 

 than ten years. It works into the timber from the level 

 of the mud to nearly the usual height of neap tides, 

 avoiding, however, the knots of the wood. In this 

 manner the w^ood is riddled in every direction, and is 

 easily acted upon by the force of the water. 



We have no doubt but that it excavates the saturated 

 wood for the purpose of food ; but we are unaware as 

 to the manner in which the canals in which it resides 

 are made. Our first impression is, that the mouth is the 

 perforating organ, and the beautiful grooved surface of 

 the under plate on the inner edge of the mandibles — 

 carefully figured by Professor Allman in his elaborate 



