36 THE BRITISH NATURALIST. [February 



I must make a further quotation from his article in the Entomologist, page 

 349. He says : — " I can quite corroborate Mr. Nevvbery's observation ; 

 .and I fully agree with M. Bedel that there are three species, abundantly 

 distinct, and easy to separate." He, however, disagrees with Mr. 

 Newbery as to the use of the term tricolor, which, " it seems to me, is a 

 mere synonym of B. riparium, as it has been recognised for the last 

 thirty-seven years." The question still remains : " Which is the true B. 

 biguttatum ? " Until we get a satisfactory solution to this problem it will 

 be useless to discuss any points bearing on the nomenclature. Suffice it 

 to say, however, that the distinctions laid down by Mr. Newbery are so 

 concise and clear that it would be decidedly best to adopt the table in 

 its entirety as printed in the British Naturalist. 



In our next issue the genera Cailistus, Chlaenius, Oodes, and Licinus 

 will be dealt with. 



THE GEOLOGY OF MILLER'S DALE. 



BY D. S. STEUART. 



( Continued from page 5.) 



Such is the history of most of the limestone dales, as affects their origin 

 and formation. 



And now, having considered how the river cuts and carves out its 

 course, grinding up and dissolving the solid limestone, taking full advan- 

 tage of every fault or crack, and never for a moment halting in its work 

 of destruction, let us turn for a moment to the action of the rain and the 

 atmosphere, two of the most important factors in the process of denudation. 



There are two ways in which this process is carried out, a chemical 

 way and a mechanical way. Winds, gales and storms, as everybody 

 knows, are very destructive ; not only do they increase the pelting power 

 of the rain, but sometimes blow down rocks. Even the gentlest kind ot 

 rain may in time do a great deal of damage to rocks and hills, moulding 

 .and grinding down their valleys in a variety of ways. 



The other, and perhaps the most important, method by means of 

 which the atmosphere and rain denude the hills and rocks is of a 

 chemical nature. 



Two of the constituents of the air, the carbonic acid and the oxygen, 

 attack the various earths, rocks, and surfaces, altering their chemical 

 composition, and converting the insoluble substances into soluble matters, 

 and the hard smooth faces of the rocks into crumbling friable masses, 

 ready to be swept away by running water or wind. 



For an illustration of this action we must climb out of the ravine (not 

 .an easy task, owing to the steepness and slipperiness of the rocks), and, 



