Hafkcr: Appendix on the Igneous Rocks. 113 



some very rertarkable hybrid rocks have been produced by 

 their mutual reactions. 



The Grainsgill Intrusion. — ^This breaks through the Skiddaw 

 Slates a little above the confluence of Grainsgill Beck with the 

 River Caldew, and is exposed in both streams. It is one of the 

 outcrops of the Skiddaw granite, and is doubtless in subterra- 

 nean connection with the others to the S.W. and S. As seen 

 in the Caldew, the rock is a granite, with both dark and white 

 mica. Farther north the white mica rapidly becomes more 

 plentiful, while the dark disappears, and the felspar is in- 

 creasingly replaced by wliite mica and quartz. The resulting 

 quartz-mica-rock, which may be termed greisen, is in Grainsgill 

 often of rather coarse texture, and it may be regarded as a 

 pegmatitic modification of the Skiddaw granite, in which the 

 felspar has been converted to mica and quartz. 



The Metamorphism of the Skiddaw Slates. — The Carrock 

 Fell gabbro has not produced any high grade of metamorphism 

 in the Skiddaw Slates on its southern side, and indeed the 

 observed boundary is clearly a faulted one. As the slates are 

 followed westward up the Caldew Valley, however, they are 

 seen to become more and more metamorphosed and visibly 

 crystalline, the change culminating in the vicinity of the 

 greisen of Grainsgill. The most important new mineral formed 

 is Cordierite,* and in the most highly altered rocks this mineral, 

 with mica and minute garnets, makes up practically the whole 

 mass. 



MOLLUSCA. 



Testacella scutulum at Brighouse, Yorks. — During 

 November 191,1, I obtained seven specimens of Testacella 

 scutidum from jMr. Lister Kershaw, Brighouse, and he informed 

 me that during the summer they could be found in consider- 

 able numbers. During the last week of February 1912, Mr. 

 Kershaw was removing some rose trees, and in the first spit 

 of ground turned over, the slug was found in large numbers, 

 though there were none in the subsoil. It has only been 

 recorded from two other places in this area, 63, S.W.Y. It 

 has been noticed for about twelve years by the gardeners at 

 Brighouse. I have a few specimens in formalin, which I shall 

 be pleased to send to any conchologist interested. — J. H. Lumb, 

 Halifax, March 15th, 1912. 



— : o : — 



The Selborne Magazine (Xo. 2O7) is largely occupied by an interesting 

 Catalogue of the Gilbert White Exhibition. 



' Some Birds new to Ireland ' is the title of an illustrated article bv 

 Prof. C. J. Patten, in The Irish Naturalist for March. 



* 'The Naturalist,' 1906, pp. 121-123. 

 igi2 April i. H 



