2 INTRODUCTION. 



in autumn by the jellies of the medusae, the storms of winter 

 and spring wholly alter the aspect. Immense banks of sea- 

 weeds mingled with black fragments of wood, coal, and 

 muddy matter cover the beach, which in many parts becomes 

 brilliantly phosphorescent at night from the zoophytes and 

 annelids on the blades of the tangles. Amidst this debris are 

 vast numbers of sponges, zoophytes, shells, starfishes, annelids, 

 crabs, and fishes which have been swept from their various 

 habitats. All storms are not equally prolific ; they also vary 

 in regard to the abundance of the several groups — a feature 

 probably due to the direction of the wind and the invasion of 

 particular sites. The waste of marine life in such storms does 

 not attract much notice ; yet it is extraordinary and so constant 

 that it may be regarded to some extent as a check upon its 

 uninterrupted development. It is, hpvvever, to be remembered 

 that even the autumnal ripple in the Outer Hebrides brings 

 countless swarms of Salpce, Velellw, Medusce, and other forms 

 to die on the beach. 



When the tide has receded after a severe storm the general 

 appearance (to select an example in October) is as follows : — 

 Besides the Fuci and other seaweeds, here and there banks 

 are formed almost entirely of tangles. Now and then one is 

 attached to the shell of a living dog whelk, a cumbrous load 

 for so tiny a mollusk ; others spring from polished pebbles 

 (bound together by their roots), from the shells of the great 

 <■<■ hAk, Tapes pullastra,Mactra solida, horse mussels, and others, 

 or bear evidence of having been forcibly torn from the rocks. 

 The latter more readily happens when the surface of the rock 

 has been coated with Balani, Lepraliir, and the purplish dif- 

 fused form of Corallina officinalis, to which the roots of the 

 tangles adhere — a fact which can be tested in a rock-pool. 

 In the interstices of the twisted roots many specimens of Saxi- 

 cava rurjosa occur, their habitations being more easily con- 

 structed, though less secure, than perforations in the rock 

 itself. Porcelain crabs can scarcely be observed in greater 

 abundance, in company with the young of the shore and 

 spider crabs ; while a few sessile-eyed crustaceans try to escape 



notice in the crevices tenanted by ( iinon and brittle stars. 



The root-fibres also give shelter to specimens of dog whelks, 



