364 Royal Society. 



4th. Most species bury themselves in the ground to increase the 

 dimensions of their shells. 



First Experiment with Helix pomatia. 

 A specimen of this species having deposited thirteen eggs which 

 were hatched during the first week of August 185'2, six of the 

 young ones were deposited in a box (having a lace cover) placed 

 in the shade. The young Helices were regularly fed every other 

 day until the beginning of December, when they buried themselves 

 in the soil for winter ; up to this period they had gradually increased 

 in dimensions to the size of Helix hispida. From December until 

 April the soil was kept dry, the box being placed in the cellar. On 

 the 1st of April they were replaced in the garden, the soil having 

 pre\nously been copiously watered. On the 3rd of April the young 

 ones appeared on the surface, being no larger in size than they were 

 in December, and although regularly fed up to the 20th of June 

 they scarcely increased, not being perceptibly larger in size than 

 they were in December. However, on the 20th of June five of 

 them disappeared, having buried themselves (with the mouth of the 

 shell downwards) in the soil ; on the 30th of June they reappeared, 

 having in ten days grown so rapidly as at this time to become equal 

 in size to Helix pisana. They agaiir buried themselves on the 15th 

 of July and reappeared on the 1st of August, having again in- 

 creased in size. From this date they did not apparently become any 

 larger, and on the 2nd of November food was withheld for the 

 winter, and at the present time (February 14th) they are in a dor- 

 mant state. Probably they will arrive at maturity by July or August 

 next. The sixth specimen did not bury itself until the 15 th of 

 August. 



Second Experiment with Helix aspersa. 



A pair of Helix aspersa having been procured in the act of copu- 

 lation on the 19th of May 1852, they were placed in confinement. 

 Each individual deposited about 70 eggs, which began to hatch on 

 the 20tli of June : these young ones grew but little during the 

 summer. They buried themselves in the soil on the 10th of October, 

 coming again to the surface on the 5th of April, not having grown 

 during the winter. In May they buried themselves (with their heads 

 downwards as with Helix pomatia, in winter they and other species 

 bui'ied themselves with the head upivards), appearing again in a 

 week double the size ; this process was carried on at about fortnightly 

 intervals until July the 18th, when they were almost fully grown. 

 It is worthy of remark that this species, as well as Helix pomatia 

 and Helix nemorulis, and probably other of the Helicse, form an oper- 

 culum at the aperture, after which they retire considerably within 

 the shell, and form a second (much thinner), behind which they 

 rest during the winter. 



It would be swelling this paper too much to describe all the obser- 

 vations in full ; it will perhaps therefore be considered sufficient to 

 remark that the process of growth within the ground takes place 



