52 



The Natuealisi^. 



arrived at from the comparison of the diagnosis of both species* 

 Specimens agreeing in every particular have been also collected by 

 J. Breidler from the classic station. 



SEMERDALE : 



NOTES OX ITS PHYSICAL FEATUEES Al^D MOLLUSCAN FAUNA, 

 By Wm. DEiST:soK Roebuck. 



Semerdale, in the vicinity of which I spent my vacation this year, 

 is— as Mr. Baker says — unicjue among the North Yorkshire Dales in 

 its shape and character. One of the contributory valleys of Wensley- 

 dale, it differs entirely in its physical aspect from such as Coverdale, 

 Bishopdale, Cotterdale, &c., all of which merge gradually into the 

 main valley. Semerdale, on the contrary, is almost completely 

 isolated : the hills which enclose it stand boldly out towards the Yore 

 and approach each other so closely, near Bainbridge, as to leave but a 

 very narrow outlet for the Bain river, which carries into the Yore the 

 the whole drainage of the dale. One consequence of the virtual shut- 

 ting off of this little basin of not more than 20 square miles of country 

 is that it contains one of the largest of the very few Yorkshire lakes, 

 which, with the usual re-duplication of syllables all meaning the same 

 thing, is called Lake Semerwater (Lake-Sea-Mere-Water). It covers 

 some 105 acres and contains various species of fish, more especially 

 bream. Trout are liliewise abundant, especially in the affluents, as 

 are also such smaller fish, as loach, minnows, &c., and crayfish swarm 

 everywhere. The lake, which has but one outlet into the Yore (the 

 Bain), is fed by numerous streams, the three most important of which 

 — Cragdale Water, Eaydale and Bardale Becks — unite before entering 

 it. The mountains which guard Semerdale — of which Counterside, 

 WetherfeU (2015 feet), Greenside (1852 feet). Fleet Moss, Cray Moss, 

 the Stake (1818 feet), and Addleborough (1564 feet), are the chief 

 summits — vary but little in height, and do not fall below 1600 feet 

 until they reach comparatively near to the main river of Yore. Bain- 

 bridge, at the outlet of the dale, is 762 feet above sea level, so that 

 the actual difference in altitude which the little basin presents is about 

 1000 feet. Geologically, so far as the imperfect maps at command 

 can show, the formations represented are carboniferous limestone 

 in the valley, presenting the usual characteristic scars," and Yore- 

 dale Rocks in the upper reaches of the tributary dales, while the 



