Correspondence — Mr. R. D. Darbishire. 93 



Great Ormo's Head, and especially on the identification, as burrows 

 of "riiolaa," of certain holes in limostono thoro and clHcwhcro. The 

 question of the correctness of tliis deterniinal.ion is of sonic inij)ortunce 

 and of real diflicnlty ; but I believe that fuller discussion will only 

 confirm the reference of these holes to I'holas, or some siinilar animal, 

 to the exclusion of Helix ; and I hope to submit some further illus- 

 tration of this subject shortly. 



In the meantime allow me at onco to prevent from Icndinj^ undue 

 support to my own side of the argument an apparent confirmation 

 of the Pholas theory, which appears in p. 494, at the end of Mr. De 

 Eance's paper. There is an error in the identification with the speci- 

 men holes under discussion of the holes in blocks of Carboniferous 

 limestone from the sea beach at Walney Island, " in each of which 

 may be seen the two perfect shell valves of a Pholas." Such a dis- 

 covery would go far to settle the question. I have, however, with 

 Mr. Bolton's permission, just examined the stones referred to. They 

 are beach boulders of limestone, which, as Mr. Bolton explained to 

 me, were imported from some place in Wales to be burned for 

 hydraulic lime in connexion with certain works at Barrow. The 

 shells are not Pholas, but the common Saxicava rugosa, quite recent. 



Specimens of recent Pholas holes in limestone are by no means of 

 frequent occurrence. My own series is not yet completely satis- 

 factory ; and if any reader of the Gteological Magazinw knows of a 

 locality where such specimens can be obtained, with living or lately 

 dead Pholades, I should be greatly obliged by his indicating it to me. 



E. D. Dakbishike. 

 ,26, Geobge Street, Manchester, 



Sir, — I think that Mr. Mackintosh must have read my paper, in 

 Vol. VI., p. 483, rather hastily, or he would not have said that I was 

 not " fortunate in meeting with very perfect specimens of lithodo- 

 mous perforations on the Llandudno Peninsula." Those which I 

 describe on page 487 are called ■' fine burrows .... one small, the 

 other about 2| inches deep, and more than an inch in greatest 

 width." Again, I speak of the burrows found within the crevice as 

 " perfectly smooth, fresh, un weathered .... all of them com- 

 pletely protected from the weather." Will Mr. Mackintosh explain 

 how Pholades could produce holes of this kind, varying from half 

 an inch to an inch in depth, and about an inch in Avidth, on the roof 

 of a horizontal crevice, about an inch wide. With regard to the 

 case, which he quotes in a note, of seventeen land shells being taken 

 from one burrow, I can only say that, having never studied the 

 politics of the " Helical State," I do not know what their laws of 

 division of labour may be. Probably, being easy going animals, 

 they are less actively selfish than those of a higher grade, and do 

 not trouble themselves when it happens that one works and another 

 shares the fruits of his labour. 1 may add that in the case which 

 Mr. Eofe mentions (Fig. 1 of my plate) there were no signs which 

 would lead me to suppose that any considerable portion of the rock 

 had been renioved, so as to expose a vertical section of any burrow, 



