92 TAYLOR : LIFE HISTORY OF HELIX ASPERSA. 



each and are agglutinated together by a colorless and sticky 

 mucus. In this species the mass of eggs deposited nearly always 

 exceeds in bulk that of the animal and shell inclusive. The 

 young attain maturity at the beginning or middle of second year. 



The eggs cannot be well preserved in spirit, like those of 

 H, potnatia ; being much softer they collapse as soon as 

 immersed. 



M. Turpin, as quoted by Moquin-Tandon, says : " The 

 thicknes and firmness of the exterior envelope depends upon 

 a great number of particles of carbonate of lime, which are 

 spread over the internal surface and crystallize in little rhom- 

 bohedrons, resembling Iceland spar ; some are isolated, some 

 in groups of 2, 3, 4, 5, or 6. The largest are rather more than 

 o"oi mill., and their angles are 105° and 75°. The inner mem- 

 brane is exceedingly thin, and quite hyaline." 



Mr. A. Nicholson (Sc. Goss. 1872, p. 238) writing of the 

 structure of the egg envelope, says : " I succeeded in separating 

 seven layers. The inner one is always as transparent as glass, 

 every one of the others is strewed, more or less closely, with 

 beautiful crystals of carbonate of lime, and it is when thus 

 divided the crystals show to most advantage, and although all 

 are cubical in structure they present a variety of forms accord- 

 ing to the angle presented to the eye by the individual crystal. 

 ...I estimate them at about 150,000 in each egg." 



Mr. Ashford remarks that carbonate of lime does not crys- 

 tallize in cubes, but one form of it, arragonite — and the mineral 

 matter of shells resembles arragonite according to Mr. Macalis- 

 ter — forms right rhombic prisms of 116° 5' and 63° 55' which 

 might on a casual view be considered cubes by an observer. 



Mr. E. J. Lowe says •' a pair of H. aspersa having been 

 procured in the act of copulation on May 19th, 1882, they 

 were placed in confinement. Each individual produced about 

 70 eggs which began to hatch on the 20th of June : these young 

 ones grew but little during the summer. They buried them- 

 selves in the soil on the loth of October, coming again to the 

 surface on the 5th of April, not having grown durhig the winter. 



J.C, iv., July, 1883. 



