THE SHORES OF BRITAIN. 67 



strewed every where around. The beauty and no- 

 velty of such a scene in the animal kingdom long 

 arrested my attention; but after twenty-five minutes 

 of constant observation, I was obliged to withdraw 

 my eye from fatigue, without having seen the tor- 

 rent for one instant change its direction, or diminish 

 in the slightest degree the rapidity of its course. I 

 continued to watch the same orifice, at short inter- 

 vals, for five hours, sometimes observing it for a 

 quarter of an hour at a time ; but still the stream 

 rolled on with a constant and equal velocity." 



Sponges, in general, appear co have little choice 

 of situation, but to grow wherever the young offset 

 or gemmule happens to drop, whether on the rock, 

 on a shell, or on a sea- weed. If two of the same 

 species, growing side by side, come into contact, 

 their edges unite, and the two form one mass, so 

 perfectly one that the most practised eye could de- 

 tect no indication of the line of union. On the con- 

 trary, if the neighbours be of different species, the 

 edges adhere by contact, but there is no union; and 

 both of the contiguous edges will grow up far be- 

 yond their natural level, like walls striving to over- 

 top each other, until the action of the waves pre- 

 vents the continuance of a mode of growth so un- 

 natural. Dr. Johnston speaks of two species of 

 Sponge which had become so intermingled in 

 growth, without being united, that, being of differ- 

 ent colours, they presented the appearance of a 

 coloured map. The same writer has figured a much- 

 branched species (Halichondria oculata), growing on 

 the back of a small crab : the latter has a grotesque 



