292 JOURNAL OF CONCHOLOGY, VOL. l6, NO. 9, JUNE, I922. 



On Carboniferous Limestone at :— 



3. Ardbraccan, Co. Meath ; H. hortensis abundant with a few 

 of the other species. 



4. Kells, Co. Meath ; H. ne?noralis on the whole is more plenti- 

 ful here than ff. hortensis. 



Mr. Welch says : " I agree with Mr. Pearce that where one species 

 is plentiful the other is rare or absent." 



On p. 304 is mentioned an exhibit by Mr. C. H. Moore of a series 

 of ZT. hortensis and H. ne?noralis found living in company at Dyserth, 

 North Wales. H. Beeston {/. Conch., vol. 12, p. 207, 1908) states 

 that in the Grange-over-Sands district of Lancashire — a district in 

 which limestone is one of the prevailing rocks — H. hortensis, which is 

 scarce in the neighbourhood, " was never found associated with H. 

 nemoralis, neither were the colonies of each near one another." 



Speaking of H. nemoralis Mr. J. W. Taylor (" Monograph," vol. 3, 

 p. 279) says: "Though usually not living in company with JI.' 

 hortensis — being really less montane in habit, and shewing a greater 

 capacity for prospering under other and more arid conditions, yet 

 there are many undoubted instances of their living in company, some- 

 times in approximately equal numbers." Again, when dealing {i.e., 

 P) 331) w^'^^ ^ hortensis, "Though occasionally found occupying a 

 common feeding-ground with H. tiemoralis, it usually congregates in 

 colonies unmixed with its ally, as it frequents moister and shadier 

 localities, and is more sensitive to drought than H. nemoralis, which 

 seems to prefer drier and more open situations." 



The frequent association of the two species in the north-east of 

 Staffordshire, in a district in which the geological and other conditions 

 vary in an extreme degree within a limited area, will, the writer hopes, 

 be of sufficient general interest to justify him in re-opening the 

 subject. 



The district over which the observations extend comprises the 

 Churnet Valley and that portion of Staffordshire lying to the north- 

 east of the Churnet Valley — generally speaking, the Churnet Valley 

 and the Staffordshire moorlands. The eastern portion of the district 

 is typical Carboniferous Limestone country ; round this comes a Ijelt 

 of Millstone Grit and Coal Measure grits and shales, a belt which 

 widens out very considerably from south to north ; and finally, in the 

 south and south-west of the area are found Triassic rocks — Bunter 

 pebble-beds and sandstones. Nowhere in the area except on the 

 limestone do H. nemoralis and H. hortensis occur, to the writer's 

 knowledge, but along the roadside walls and hedgerows— a circum- 

 stance which very probably indicates that the two species have, 



