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disappear, and Fucus vesiculosus becomes greatly stunted, and no 

 longer exhibits its characteristic double rows of bladders. But for 

 mile after mile it continues to exist, blent with some of the hardier 

 Conferva?, until at length it becomes as dwarfish and nearly as slim of 

 frond as the Conferva: themselves ; and it is only by tracing it through 

 the intermediate forms that we succeed in convincing ourselves that, 

 in the brown stunted tufts of from one to three inches in length, which 

 continue to fringe the middle reaches of the lake, we have in reality the 

 well-known Fucus before us. Rushes, flags, and aquatic grasses may now 

 be seen standing in diminutive tufts out of the water ; and a terrestrial 

 vegetation at least continues to exist, though it can scarcely be said 

 to thrive, on banks covered by the tide at full. The lacustrine flora 

 increases, both in extent and luxuriance, as that of the sea diminishes ; 

 and in the upper reaches we fail to detect all trace of marine plants : 

 the Alga?, so luxuriant of growth along the straits of this ' miniature 

 Mediterranean,' altogether cease ; and a semi-aquatic vegetation at- 

 tains, in turn, to the state of fullest development anywhere permitted 

 by the temperature of this northern locality. A memoir descriptive 

 of the Loch of Stennis and its productions, animal and vegetable, 

 such as old Gilbert White of Selborue could have produced, would 

 be at once a very valuable and curious document, important to the 

 naturalist, and not without its use to the geological student. 



" I know not how it may be with others; but the special phenomena 

 connected with Orkney that most decidedly bore fruit in my mind, 

 and to which my thoughts have most frequently reverted, were those 

 exhibited in the neighbourhood of Stromness. I would more parti- 

 cularly refer to the characteristic fragment of Asterolepis, which I de- 

 tected in its lower flag-stones, and to the curiously mixed, semi-marine, 

 semi-lacustrine vegetation of the Loch of Stennis. Both seem to bear 

 very directly on that development hypothesis, — fast spreading among 

 an active and ingenious order of minds, both in Britain and America, 

 and which has been long known upon the Continent, — that would 

 fain transfer the work of creation from the department of miracle to 

 the province of natural law, and would strike down, in the process of 

 removal, all the old landmarks, ethical and religious." — p. 9. 



Before we introduce to the notice of the reader the author's inge- 

 nious application of the above facts to the development hypothesis, 

 let us accompany him on a more extended tour of observation, 

 wherein we shall find that the boundary line between the vegetation 

 of land and water, so clearly defined upon the shores of the Loch of 

 Stennis, as distinctly separates the marine and littoral floras of the 

 Vol. hi. 5 a 



