76 Mr. BENNETT on a peculiar Property 
the present notice appears to be the Echinus saxatilis of Linnzeus ; 
but the character assigned to this species by that distinguished 
naturalist is so indefinite as to preclude the possibility of cer- 
tainty on this point. It however coincides precisely with the 
description given by Leske of his Cidaris rupestris, and with 
Lamarck's specific character of his Echinus lividus; both of 
these authors (the latter with a mark of doubt) referring to this 
species of Linnæus as synonymous with theirs respectively. The 
appositeness of the trivial names both of Linnæus and of Leske 
to the habitat of the animal in question, might lead to the 
suspicion that they were acquainted with the property noticed 
above: but there is no reference in either of them to any au- - 
thor by whom it has been mentioned. Rumphius, indeed, de- 
scribes the Echinus saxatilis as inhabiting “the holes and cavi- 
ties of corals, in which they sometimes grow to such a size that 
it is impossible to pull them out." But these words evidently 
imply his opinion that it sought holes previously formed, in 
which it increased in bulk ; and do not even hint at the con- 
clusion, that itself formed and enlarged the cells in which it 
dwelt. 
Whether the species of Echinus described and figured by 
Rumphius, and referred to by Linnæus as synonymous with his 
E. saxatilis, be identical with the one which inhabits the western 
coasts of Ireland, may probably, on account of their geographi- 
cal distribution, be regarded as doubtful, the former having 
been discovered in the Indian Seas. "The species of this genus 
are, however, so difficult to determine, and so little understood, 
that I will not at present venture to decide upon this question. 
If not identical, they are at least analogous; and I may mention 
as a fact bearing upon this point, that I have lately seen a spe- 
cimen of Echinus, brought by Captain King, F.L.S., from New 
Holland, 
