362 Prof. AUman on Chelura terebrans. 



discovery^ and which it is often ahnost impossible to avoid, than 

 to view it as pointing towards any real distinction. 



Notwithstanding this anticipation, I have yet deemed it advi- 

 sable to publish my original paper, making of course the name 

 which I had given to the Crustacean, yield to that which its dis- 

 coverer had previously imposed upon it. To this determination 

 I have come, not only from the fact of my researches having been 

 conducted quite independently of any knowledge of what had 

 been previously done in the matter, but also because, from having 

 had abundance of living specimens at my disposal, my details are 

 considerably fuller than those of Philippi, while they do not, as 

 has just been said, correspond in all points with the description 

 given by this naturalist. 



Specimens from the Kingstown locality have been for some 

 years in the collection of Mr. Robert Ball, who must be viewed 

 as the original discoverer of the crustacean as an inhabitant of 

 the British seas, though it is in a paper read by Mr. Mullins in 

 January last before the Institute of Civil Engineers in Ireland, 

 with the view of eliciting suggestions for preserving timber from 

 the attacks of this and other destroyers, that is to be found the 

 first record of the animal as an addition to our fauna. 



In the year 1834 Mr. Thompson noticed the occurrence in 

 the same place of Limnoria terebrans^ ^ and this animal may still 

 be detected proceeding along with the subject of the present 

 paper in its ravages, but quite outdone by the latter in the work 

 of destruction. 



The characters of the genus may be comprised in the following 

 enumeration : — 



Chelura, Phil. 



Gen. Char. Body not compressed. Head distinct. Superior 

 antenna shorter and more slender than the inferior, and con- 

 sisting of a peduncular portion which supports two unequally 

 developed rami; inferior «w/ew?i« large, not divisible into a di- 

 stinct peduncle and ramus. Mandibles strong, palpigerous, 

 furnished with a molar tubercle with transverse ridges. First 

 pair of maxilla strong, pyramidal, palpigerous; second pair 

 lamelliform. Maxillary feet large, bearing a palp-like stem, 

 and united at their origin so as to constitute a great opercular 

 lip covering all the other organs of the mouth. Thoraxf com- 



* Thompson (Wm.) on Teredo navalis and Limnoria terebrans in Edinb. 

 New Phil. Journ. January 1834. 



f It is deemed advisable throughout the present paper to adopt the gene- 

 rally received terminology, though the beautiful researches of Erichson 

 (Entomographia) have altogether disproved its correctness, the thorax of 

 carcinological writers generally being according to this philosophic natura- 

 list composed almost entirely of segments really belonging to the abdomen. 



