40 Correspondence — Rev. T. G. Bonney. 



the burrowings in Limestone which. I described as occurring in 

 Millers Dale. Perhaps he may have overlooked them, or possibly, 

 as they were not numerous, some other person may have broken 

 them away. I was reluctantly obliged to detach a specimen myself 

 (which I send herewith) for the confutation of the incredulous. To 

 insinuate that I do not know 'Toadstone ' from 'Limestone,' or should 

 write in a scientific periodical after an examination called ' careful ' 

 by myself, but in reality so hurried as to mistake the one for the 

 other, or indeed the " vesicular cavities " of toadstone for " the 

 borings of animals," attributes to me ignorance so gross, or careless- 

 ness so reprehensible, that Mr. Brown might as well have said that 

 he considered me unworthy to write F.G.S after my name. 



St. John's College, T. G. Bonnet. 



Cambridge, Dec. 5. 



P.S. — With regard to the principal subject of Mr, Brown's com- 

 munication, I may remark that the following instances confirm, if it 

 be needed, the idea of some, at least, of the Toadstones not being 

 intrusive. (1). In a small cliff close by Litton Mills, at the opening 

 of Cressbrook Dale (left bank), we have the following section : — 

 (a) High talus overgrown with bushes, showing projecting ledges 

 of limestone : (b) Clifi" of Toadstone, upper part sandy and de- 

 composing, lower part more solid and amygdaloidal : (c) well 

 marked bed of very compact Toadstone : (d) sandy and shaly band, 

 volcanic ashes : (e) ashy bed, nodular and concretionary in places, 

 with fossils, Spirifera Productus, etc. : (f) Limestone, very compact, 

 perhaps somewhat altered. (2). In descending by the road that 

 leads over the flanks of the Heights of Abraham from Matlock Bath 

 to Bonsall, after quitting the sheet of Toadstone that caps the hill, I 

 observed many blocks in the wall containing volcanic ash. One 

 variety is a purple rock of clayey fracture, containing angular or 

 subangular fragments of limestone, and yellowish brown or greenish 

 bits and specks, which I believe to be decomposing:: volcanic ash ; the 

 other a calcareous rock (? brecciated in places) with many specks of 

 greenish grey and brown colour, also decomposing ashes. This bed 

 contains fragments of small crinoids. If I mistake not, both these 

 beds are exposed in situ by the road-side a short distance apart, and 

 about fifty yards from the first cottage in Bonsall village. — T.G.B. 



In the Geological Magazine for June last (Vol. VII., p. 267) we 

 published an article on supposed PAoZas-burrows in Millers Dale, 

 by the Kev. T. G. Bonney, M.A., F.G.S. 



Another article " on the supposed oocurrence of P^oZas-burrows 

 in the upper parts of the Great and Little Ormesheads," by the same 

 author (accompanied by a Plate), appeared in Vol. VI., 1869, p. 483. 



Mr. Bonney's observations tend to disprove their P/io/as-origin, 

 and to support the conclusions of M. Bouchard-Chantereaux, 

 Miss Hodgson, and others, that they are the work of Helices. 



In a letter published in the December number of this Magazine 



