MARINE AMTHEOPODS 293 



locally in such numbers that it may be found under nearly every 

 stone of any size. In fact, we have searched two or three localities 

 on the south-west coast where this crab is not only extremely 

 numerous, but is at the same time almost the only species to be 

 found ; and it seems not unlikely that the pugnacious Lady has 

 been the means of driving the less formidable species from its 

 favourite haunts. 



When you disturb a Velvet Crab it will immediately raise itself 

 in a menacing attitude, stretching its brightly coloured pincers as 

 wide apart as possible, and then it will either retreat backwards, or 

 even make a firm stand, ready to strike as soon as it is threatened 

 with an attempted touch. Try to grasp it, and its two powerful 

 weapons of defence are brought together with lightning-like rapidity 

 giving one a decidedly smart blow, possibly followed by a grip of 

 great tenacity for a creature of its size ; but, should it miss its aim, 

 its pincers strike together with a sharp click, only, however, to 

 extend at once in preparation for the next attempt. 



It will be observed that the walking legs of this crab are all 

 flattened, and that while the first three pairs terminate in sharp, 

 lance-like claws, the last pair are broad and fringed with hairs, thus 

 showing their close relationship to the swimming crabs. In fact, 

 the same genus contains British species which are popularly known 

 as Swimming Crabs. 



One of the swimmers is represented in fig. 4 of Plate VI. It is 

 generally known as Henslow's Swimming Crab or the Nipper, the 

 scientific name being Polybius Henslowii. The carapace of this 

 species is quite smooth, thus enabling the crab to move through the 

 water with less resistance, and the walking legs, particularly the 

 last pair, are flattened and fringed for use as paddles. It, is said 

 that this crab can raise itself from the bottom to the surface of 

 moderately deep water by means of the swimming feet, and that it 

 preys on fishes which it pursues with some vigour. 



Other crabs than those briefly described will reveal themselves 

 to the sea-side collector, but we have not the space to introduce 

 them here. Sufficient information has been given, however, to 

 enable the reader to broadly classify his specimens a matter of 

 more importance to the young naturalist than the mere naming of 

 species. 



Leaving the crustaceans now, and passing for a moment to the 

 Arachnoidea the second great division of the arthropods we shall 

 briefly describe the Shore Spider (Pycnogonum littorale), which is 



