378 Correspondence. 



well-formed, tabular crystals of Wulfenite (Molybdate of Lead) , at 

 the Treffgarn Eocks, between Haverfordwest and Fishguard. They 

 occur in small cavities, which are irregularly dispersed through the 

 rock (a felstone according to the geological map of the district), are 

 of a brown or honey-yellow colour, semi-transparent, with the edges 

 bevelled, and in form answer to fig. o in Phillips' " Mineralogy " 

 (4:th edition), I also obtained a substance of a greenish-grey colour, 

 disseminated in small veins and patches, which is probably the same 

 mineral in a massive form. Minute but exceedingly perfect crystals 

 of tin likewise occur, similarly to those of the Wulfenite ; but, as 

 far as I have been able to observe, in a separate portion of the rock. 

 I may as well mention that I have recently found some fine black 

 crystals of Blende (sulphide of zinc) at the tmmel near the Patchway 

 Station on the Bristol and South Wales Union Eailway. I am not 

 aware that this mineral has been met with before in Gloucestershire, 

 or the neighbouring counties. — I remain, dear Sir, yours very truly, 



Spencer George Perceval. 

 Severn House, Henbury, Bristol, June llth, 1866. 



THE EEV. T. G. BONNET ON "TRACES OF GLACIERS IN THE 

 ENGLISH LAKES." 



To the Editor of the Geological Magazine. 



Dear Sir, — In reference to the paper by the Eev. T. G. Bonney 

 on "Traces of Glaciers in the English Lakes" in the July 

 number of the Geological Magazine, the author will find that 

 the subject has already been discussed to some extent by Mr. E. 

 Chambers, and more recently by myself in a paper, with illustrations, 

 " On the Glacial Vestiges of the Lake District," published in Vol. 

 xi. of the "Edinburgh New Philosophical Journal," (1860), and 

 that the remarkable ice- worn rock on the north side of St. Mary's 

 Churchyard, Ambleside, is figured both in that paper and subse- 

 quently in Lyell's "Antiquity of Man," p. 269. The Glacial phe- 

 nomena of Wastdale (or Wast-water), not the "Wastdale" of Pro- 

 fessor Phillips' Memoir, are also described in one of the last 

 numbers of your Magazine's predecsssor — " The Geologist ; " and the 

 whole subject, with its relations to the glacial phenomena of North 

 Wales, as worked out by Professor Eamsay, is touched upon in a 

 recent number of the " Memoirs of the Literary and Philosophical 

 Society of Manchester" (1864). The exact reference to which, absence 

 from home prevents me from giving. I hope Mr. Bonney will not 

 suj)pose that, in sending this information, I wish to underrate what- 

 ever is new and interesting in his paper, which is far from my 

 intention. 



I remain, very truly, yours, 



Edward Hull. 



DouaLAS, Isle of Man, %th July, 1866. 



