220 



TEMPERATURE. 



higher end of the Adriatic, as also of the southern 

 portions of the Black and Caspian seas. 



The Celtic province of Ed. Forbes was formed to 

 include under one term a fauna which, under many 

 favourable conditions, becomes peculiarly rich ; 

 southern forms begin to show themselves, and no- 

 where is the direct relation of distribution to tem- 

 perature better shown than here. 



Pursuing for the present the subject of low tem- 

 peratures, sea water, as is well known, seldom freezes 

 in our Celtic region ; when this happens, as it did 

 in the winter of 1854-5, we had a good illustration 

 of the effects of cold on a portion of a marine fauna. 

 The shallow pools of water over the interval between 

 tides and the surfaces of the mud-banks with their 

 growths of weed, were all frozen hard ; the animals 

 frequenting this zone mostly perished, and for months 

 afterwards there were parts of our southern coast 

 where lines of littoral shells, with their putrid con- 

 tents, stretched in thick bands along the upper tidal 

 line. 



A writer in the "Witness" newspaper, perhaps the 

 late Hugh Miller, gave a graphic description of the 

 effects of the cold of the same winter on the Mol- 

 lusca of the Frith of Forth. Oyster farmers know 

 full well, to their cost, the havoc of a few hours' cold 

 on their uncovered fields. 



The weedy surfaces of our mud-banks swarm 

 with small molluscous vegetarians, whole tribes of 



