338 Dr. W. C. M'Intosh on the 



the latter being recognized by a depression. The common 

 shore-crab occurs 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 cheke, 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. In these 

 circumstances the body is coated with mud, which fills up the 

 irregularities of its conformation, and loads the abdominal 

 feet and hairs j yet the crab is vigorous and healthy, and out- 

 lives sanitary apprehensions. 



Under almost every stone within reach of the tide young 

 specimens occur. At low water the full-grown crabs seek the 

 hiding-places just mentioned, or shade themselves under the 

 blades of the seaweeds in the rock-pools. Occasionally one is 

 found adhering to the soft body of a moulting brother and, 

 cannibal-like, devouring the branchiae, new carapace, and other 

 soft organs with savage pertinacity, while the old shell has 

 not quite fallen from its victim. Moulting shore-crabs are 

 generally found alone, as if aware of their helplessness, and 

 dreading, with some degree of correctness, the voracity of 

 enemies and even unscrupulous relations. Very slight injury 

 kills them in this condition ; and of course, for a time, they are 

 incapable of defending themselves from even weak assailants. 



The shore-crab is found in pools at the East Rocks where no 

 other marine articulate of the same class occurs ; and the water 

 cannot but be brackish, since the pools are not filled by ordinary 

 tides, and fresh streams from the crags flow in the neighbour- 

 hood. In these resorts the colour of the crab is not so pretty, 

 being of a muddy green with pale limbs ; and the specimens 

 in the highest pools are generally small. It is not surprising, 

 however, to find them in sucli places, after watching their 

 activity in the innumerable brackish lakes of the Outer 

 Hebrides, and their evident comfort in perambulating the 

 muddy flats even where streams of fresh water abound. 



