398 
CRUSTACEA. 
Genus Chelura. 
C. terebrans, Philippi. 
All that has been published on this species has already appeared in the 
Annals ; Philippi’s paper, in which it was first described, having been 
translated and republished in the fourth volume ; and Professor Allman’s, 
introducing it as an inhabitant of the British seas, having a place in the 
number for the month of June, 1847. I have therefore only to offer a few 
remarks bearing on the species as found at Ardrossan. 
Limnoria and Chelura are both present in a piece of wood from Kings- 
town Pier, Dublin Bay, given me in 1842 by Dr. Ball, as well as in the 
wood from Ardrossan. 
Both species bore in the direction of the grain of the wood, and their 
cells are quite alike in character : I perceive no mark of distinction when 
the animals are of equal breadth. The first piece of wood pierced by the 
Chelura which I had an opportunity of examining — that from Kings- 
town — contained the excavations of large adult individuals. The borings 
of these were so considerably larger than those of the Limnoria which 
had come under my notice, as to lead me to believe that the difference in 
the size of the aperture would at once distinguish the working of either 
species. The piece of wood from Ardrossan, however, not only proved 
that this was no criterion, but — from the circumstance of the Chelurce 
being small, and less in breadth than the Limnorice — that theirs were 
rather the smaller cells. 
Both the Crustaceans, like the Teredo and Xylophaga, labour harmoni- 
ously together in the work of destruction, and are mingled in the wood 
as if they were all of one species. 
They can be readily distinguished from each other either when alive or 
dead, the Chelura being of a reddish, the Limnoria of a pale greyish yel- 
low hue resembling that of light-coloured pine or fir. As they retain their 
colours after death, we may even years afterwards distinguish the two 
species in the excavations which they had formed in timber subjected to 
their ravages. From this circumstance, added to that of their burrows 
being formed in the closest contiguity, and many of the creatures 
dying in them after the timber has been removed from the sea, we may 
in our museums display whole catacombs of them as closely packed as 
ever were mummies in the best-tenanted tombs of Egypt. And the 
Crustaceans have this advantage, that 
“Each in his narrow cell for ever laid ” 
remains perfect as in life, without the aid of any preservative. 
On first learning from my friend Professor Allman that the two 
species were found associated together, I re-examined — for the purpose 
of ascertaining whether the Chelura might not have been overlooked — all 
the wood that I had preserved on account of Limnoria borings, but in 
none of it was the former species to be detected. This wood was all pine, 
and from Portpatrick, Donaghadee, and Belfast Bay : from the first- 
named places obtained in 1834, and from the last in the present year. In 
the more marine parts of this bay I was not surprised to find that the 
Limnoria existed. I had however hoped, that where the admixture of 
fresh with sea-water (if such take place) should be very great even at 
full-tide, and where at low-water the former only prevails, wood-work 
would be free from its attacks, but such I regret to state is not the case. 
For the purpose of testing this, I requested my friend Edmund Getty, 
