CRUSTACEA, 153 



Order Podophthalmata. 



The stalk-eyed Crustacea of St. Andrews are cliiefly north- 

 ern in type ; and though the species are not numerous, many 

 are very plentifully represented. The most important forms 

 here, as elsewhere, are the edible crab and the lobster. Both 

 are caught in considerable numbers along the border of the 

 rocks by means of the ordinary crab-pots, which are generally 

 baited with fragments of grey gurnards and other fishes of 

 little value. The most successful ground is off the East 

 Rocks, though a very large lobster in the Museum of the 

 University was procured to the north of the West Rocks. 

 Some of the fishermen have an idea that if a lobster enters 

 a trap first, none of the edible crabs will venture beside it, 

 whereas a lobster will invade the crab-pot though a dozen of 

 the former are already there. Constant attacks seem to have 

 diminished the numbers of both species, and especially of the 

 lobster. 1 have never seen any of the latter between tide- 

 marks ; but young edible crabs are common under ledges and 

 stones, and even in tlie sand at low water, their presence in 

 the latter being recognized by a depression. The common 

 shore-crab occm-s everywhere along the rocky border, both 

 between tide-marks and in the laminarian region. This ubi- 

 quitous species lurks in the retired apertures and clefts amongst 

 and under the rocks, especially where these have a bottom of 

 soft sand or dark mud. In this it buries itself so as to retain 

 moisture in the gills, while the anterior part of the carapace is 

 uncovered, probably for quiet observation. In these situations 

 it quite understands an attempt to capture it ; and there are 

 few examples, if any, in which, by seizing the crooked iron 

 with its chelae, it has allowed itself to be drawn out. On the 

 contrary, it endeavours to escape with much effort and consider- 

 able agility. Even when quite invisible its presence may be 

 detected by striking the rock, when the grating of the carapace 

 is heard as the animal retreats. It is often to be found in 

 positions which seem any thing but comfortable — amongst 

 blackened and putrefying animal remains, in muddy and 

 odoriferous pools tenanted by none except itself. Tn these 



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