^94 JOURNAL OF CONCHOLOGY, VOL. I4, NO. ID, AtRlL, 19I5. 



backwards by the movement of the muscles of the foot. How the 

 animals roll over on their backs before hibernating I have not 

 yet discovered. 



The first shell to come from its winter quarters appeared on 

 2nd February, 1913 ; but all had not re-awakened till 3rd March. 

 Two of the largest specimens were isolated and attained their full 

 growth during June and July, 1913. They were seen pairing on 

 14th August; but no eggs were laid during this year. One speci- 

 men went into hibernation on loth October and the other later 

 in the same month. 



By this time almost all the F i generation were full-grown, al- 

 though a few did not reach full growth until 19 14, and all resembled, 

 more or less, the typical parent from Carrickfergus. 



On ist February, 1914, one specimen came out of hibernation; 

 but not until 30th March did its companion make its reappear- 

 ance. On 31st March, the following day, they paired and remained 

 thus all day. Again at 7 p.m. on 8th of May they were seen 

 pairing and were still thus at 1-30 p.m. on the following day. 

 Eggs were laid on 3rd June under a fiat stone which I had placed 

 on the sand. One parent died on the 12th June: presumably 

 that which had deposited the eggs. About seventy-five young 

 hatched out on 27th June, and many more on the following days. 

 On 15th July another "family" appeared, the outcome of a batch 

 of eggs laid by the remaining parent during June. As soon as 

 growth commenced, it was observable that some of the young shells 

 were of a greenish colour and not of the pale amber hue of the 

 typical form. As the amber coloured specimens grew they developed 

 the normal brown banding and were killed at once to prevent 

 over-crowding. On T4th August the exalbida examples were easily 

 distinguished from their pinkish-brown brothers and on that date 

 all specimens were killed but twenty (eleven white and nine 

 brownish) with which I intend to carry on further experiments. 



In all 311 examples were reared and assuming that the originals 

 from Dorking and Carrickfergus were each homozygous in regard 

 to their colouring, white and brown respectively, the F 2 generation, 

 theoretically, should have consisted of 77"7S exalbida and 233"25 

 type. The actual figures, therefore, are most interesting, namely 72 

 white and 239 brown. Several at least died before their colour 

 could be ascertained with certainty and are not included in the figures 

 given. These figures came as a great surprise to me, as I did not 

 expect to get more than a few white examples in the F 2 generation. 

 It is not easy to see how a stray white specimen could be of a 

 pure strain, unless the var. exalbida is a homozygous recessive form. 



