380 
CRUSTACEA. 
as extremely rare. The several Irish examples I looked to with reference 
to their sex were likewise males. It may be remarked, that in this spe- 
cies the females might, from the very narrow form of the abdomen, be 
without due attention regarded as males. 
In the month of September, 1835, I obtained several small living spe- 
cimens of Atelecyclus (carapace about 2 lines in length) in rock-pools 
accessible at low-water at Bangor, County Down. They differ a little in the 
contour of the shell (which is not so round), and in the form of the teeth 
between the orbits, from the adult A. heterodon , but on account of their 
diminutive size, and in the absence of specimens of all ages for com- 
parison, it would, I conceive, be rash to consider them otherwise than this- 
species. 
Genus Corystes. 
C. Cassivelaunus. 
“ Found on the shore at Cushendall Bay,” Templeton. Marked as 
“ Irish ” in Mr. J. Y. Thompson’s collection. This species is commonly 
found after storms on the sandy shores of the North and East of Ireland. 
In the month of August, 1836, a number of very small specimens were 
dredged from a sandy bottom in the open sea off Dundrum, Co. Down, 
by Mr. Hyndman and myself. The smaller the individuals of this species, 
the antennae are the longer in proportion to the size of the body : some 
of these with the shell or carapace 3 lines in length have the antennae 6 
lines long ; on this account the young present a very singular and gro- 
tesque appearance : none of those taken on this occasion had the carapace 
more than 6 lines in length. In the stomach of a smooth dog-fish (Mus- 
telus Icevis ), captured in Belfast Bay, I found a perfect adult specimen of 
this crab. 
' Dr. J. L. Drummond informs me that he has frequently taken this 
species at Bangor at neap-tides, when he detected it by the antennas 
(which were always in contact with each other) being protruded above 
the surface of the sand for nearly their whole length. Dr. Ball, wdio has 
found these crabs in abundance at Youghal and Dublin, has seen them 
shake themselves down in the sand so as to conceal all but the antennae 
as described. He is of opinion that the antennae are not thus protruded 
for any special object, but 'simply that the animal feels itself sufficiently 
concealed when the body is covered. 
Carnlough beach, W. T., Corystes. I find a few perfect specimens, every 
day, Newcastle, Co. Down, July, 1851. 
Oct. 9 th, 1851. Newcastle, Co. Down, Corystes. Severe gales at the 
beginning of this month cast many ashore. 
Genus Thia. 
T. polita, Leach. 
Galway, burrowing in sand. Professor Melville. 
