300 Correspondence. — Mr. G. H, Kinahan. 



mesial fold of generally three plaits. The hardness of the rock 

 makes it difficult to obtain perfect specimens, but in those which he 

 exhibited the beak appears to be more incurved than in the typical 

 specimens. He proposed the name of B. Crossii for this variety. 

 The specimens were obtained from the inferior Oolite of Appleby, 

 near Brigg, Lincolnshire. 



The Rev. J. F. Blake, M.A., F.G.S., communicated a paper on the 

 "Eed Chalk," sketching out its geographical range. Its most 

 southerly appearance is near Hunstanton ; from thence it is traced 

 through Lincolnshire to South JFerriby, crossing to the north of the 

 Humber (Mr. Blake had seen it at VVelton Dale) ; thence it skirts 

 the base of the Chalk to Elloughton, then a little to the north of 

 South Cave, and several times in the hills between there and North 

 Newbald, and at Sancton ; it is said to occur at Bishop Wilton, and 

 onwards to Grimston, and thence with a change of strike by 

 Knapton eastwards to Speeton. He remarked that the palaeonto- 

 logical evidence was almost irresistible for its Green-sand age. 



The Hon. Payan Dawnay was elected President of the Club for 

 1870, and as Vice-Presidents Mr. J. Leckenby, F.G.S., and Mr, E. 

 Wood, F.G.S. 



coi^i^ESiPoisriDZEn^oiE. 



THE MINERAL-BEARING STRATA OF THE SOUTH-WEST OF IRELAND. 



Sir, — In tbe Supplement to the Geolo'gical Magazine for May, 

 1870, Mr. S. Hyde, writing on this subject, compares the mines on 

 the Bear promontory with those on the Crookhaven and Sheep's-head 

 promontories. To me, however, this does not seem to be a fair com- 

 parison, as Mr. Hyde, along with previous writers on the subject, 

 neglects to mention one of the most important featui'es in regard to the 

 first-named locality, namely, the large development of ingenite rocks. 



These rocks were intruded subsequent to the deposition of the 

 " Coppery Zone" in the so-called Devonian rocks, and to the ingenite 

 rock, I believe, is due the productiveness of the lodes at Allihies and 

 thereabouts, while in the promontory of Crookhaven, where none of 

 these ingenite rocks have been found, the lodes are, comparatively 

 speaking, poor. 



What seems to be in favour of this theory is the fact, that in most 

 if not all the places where rocks of this age occur that have not been 

 subsequently invaded b}^ ingenite rocks, although minerals are com- 

 mon, they are not collected into the lode, but are disseminated through 

 the beds, while in those places where the newer ingenite rocks now 

 exist, the minerals principally occur in the lodes and are not dissemi- 

 nated through the rocks. This would account for the ores in lodes in 

 Cornwall, Di3Von, Allihies, &c., Avhile in other places, that appa- 

 rently ought to be as good "ground," few or no paying lodes occur. 



G. H. KINAHAN, 

 Recess via Galwat. H.M. Geological Survey of Ireland. 



Errata. — In Prof. T. Rupert Jones'e article last montli we notice tbe followino' 

 Errata: p. 217, line 17, for Fig. 1, read Fig. 3 ; p. 218, line 26, for sharper, read 

 blunter ; p. 218, line '67, /or larger, read smaller. 



