ATRBREATHING M0LLUSK8, 
73 
The common snail, Helix aliolairis, is a type of the air- 
breathing mollusks. Fig. 86 represents this snail of natu- 
ral size, in its shell. The opening to the lung is seen at 
and at B is represented the heart and lung of the garden 
slug (Lwiax flavits). 
The eggs of the ])ond-snails are laid in transparent cap- 
sules attached to submei'ged leaves, etc. 
Those of Physa heterostroplia are laid in 
the early spring, and three or four weeks 
later from fifty to sixty embryos witli 
well-formed shells may be found in the 
capsule. 
The eggs of Limnmns are laid late in 
the spring in capsules containing one or 
two eggs, and surrounded by a mass of 
jelly. 
Land-snails and slugs lay their eggs 
loose under damp leaves and stones, and fiq. 85.— Slug; natural 
development is direct, the young snail 
hatching in the form of the adult. 
Various shells, such as Marginella, Turiinella, etc., are 
4 
Fig. 86.—^, oommon snail, natural size; j5, the heart and lung". 
strung in bracelets and armlets by savages. Cjjprcea mo- 
neta, the cowry (Fig. 87), is used for money, and other 
shells are worked into various shapes for wampum or abo- 
