igoo- 1 WkIvCH . — A bnormal Shells of Helix nemoralis. 1 65 



These were evidently some of the " oldest inhabitants," as 

 the epidermis was quite gone. Of the fourteen in all collected 

 alive, eight weighed over 20 grains, and the others, younger 

 shells of the first or second year with lip barely completed, 10 

 grains or over. The only other place where I got this variety 

 over 10 grains in weight was at Islandmagee, Antrim coast ; 

 one of three there weighed 15 grains. But my friend, Mr. 

 Edw^ard Collier, of Manchester, obtained one at Folkestone of 

 17 grains, and another at Bally vaughan, Co. Clare, of the 

 same weight, with two much lighter ones. Three specimens 

 in his collection from Peel, Isle of Man, weigh under 6 grains 

 each, and four others from various localities average 8 grains. 



The typical shells at Bundoran are rather strong and heavy 

 (as will be seen from the weights of others, from coast 

 localities also, that I give for comparison), but though I 

 examined hundreds, I could find none over 34 grains, and only 

 one of that, the average of the four best being 28 grains, of the 

 ten best 25 grains, much under the weights of the variety 

 respectively. The discrepancy is still greater in the following, 

 which were also selected from the heaviest specimens I could 

 get in each case. Of course, though all were alive when 

 collected, the shells were well cleaned and dried before 

 weighing. 



WEIGHTS IN GRAINS. 



Grains. 

 Portrush dunes. (Out of alarge number, two weighed 



17 each.) Average of nine best, . . . = n 



Whitepark Bay, Co. Antrim. Average of ten, . = 9J 



Portstewart dunes, Co. Derry. (One 17.) Average 



of 10, . . . . . . . = 10 



St. John's Point, Co. Down. (None over 13.) 



Average of 12, . . . . . = 10 



Newcastle, Co. Down. (Shells are thin on dunes 



here, especially at southern end, and the lightest 



I have collected anywhere.) Average of ten, • = 4 



These were the ordinary banded and unhanded forms 



(mostly libelliUa), and they were all collected at places w^here 



there seemed to be an abundant food-supply —the main factor, one 



might expect, in the formation of a heavy shell. In the case of 



the Bundoran specimens, on the contrary, all of the heavy 



A 2 



