806 THE ZOOLOGIST. 
that of I. dorhynchus, although Bell figures it as proportionately 
smaller and more simple, which we have not found to be the case 
in the large number of specimens which we have examined. The 
legs are very long, much longer than those of either of the other 
two species of the genus; the anterior pair are particularly 
striking in this respect, and mark the distinctiveness of the 
species at a glance. Its most remarkable and characteristic feature 
is the existence, in the male, of a polished calcareous tubercle on 
the sternum, between the bases of the leg joints: this tubercle is 
peculiar to the genus, and is only represented in one other known 
species from the Mediterranean, viz., I. thoracicus, in which it 
forms a plate. ‘“Sternum du mile, garni en avant de deux plaques 
calcaires ovalaires réunies par une piéce médiane.’’* 
Bell speaks of this species as being ‘“‘ extremely rare,” and 
gives solitary instances of its capture, stating that it was dis- 
covered by the late Mr. Cranch on the west coast of Devon and 
Cornwall: it has since been recorded from Shetland (deep water), 
Dublin, Belfast, Clifden, and the Hebrides, and there is no doubt 
that it is less common than Jnachus dorsettensis, and may be 
looked upon with J. dorhynchus as ‘“‘a good thing.” We have 
fortunately obtained a fine series of this interesting crustacean, 
many of which were taken from the deep part of the English 
Channel, off the Sussex and Dorset coasts. Another locality from 
which we obtained it was off Guernsey in a crab-pot; and this 
leads to a remarkable instance of extreme locality, which may 
possibly account for the supposed great rarity of this species. 
A fisherman who worked regularly a number of crab-pots stated 
that this crab always occurred in quantities in one particular 
pot, and never by any chance in any others in the locality, not 
even in the next pots on either side. Upon repeated visits we 
found this to be literally true, and this one little spot is the 
only place there upon which we can rely to obtain this species. 
Another of this same set of pots was also similarly resorted to by 
a starfish, Ophiocoma granulata, this instance helping out the 
other in proving that this extreme limit to localities does most 
certainly exist as much on the sea bottoms from some favourable 
cause or other, probably the presence of congenial food, as it 
does on land where the presence of certain conditions favours 
* Milne-Edwards, ‘ Hist. Nat. des Crust.,’ vol. i., p. 289. 
