The number of eggs varies greatly, being highest in the Pelecypoda. In _Ostrea edulis_ it has been estimated at from 300,000 to 60,000,000; in _Anodonta_ from 14,000 to 20,000; in _Unio pictorum_ 200,000. The eggs of _Doris_ are reckoned at from 80,000 to 600,000, of _Loligo_ and _Sepia_ at about 30,000 to 40,000. Pulmonata lay comparatively few eggs. _Arion ater_ has been observed to lay 477 in forty-eight days (p. 42). Nests of _Helix aspersa_ have been noticed, in which the number of eggs varied from about 40 to 100. They are laid in little cup-shaped hollows at the roots of grass, with a little loose earth spread over them. The eggs of _Testacella_ are rather large, and very elastic; if dropped on a stone floor they will rebound sharply several inches. The _Cochlostyla_ of the Philippines lay their eggs at the tops of the great forest trees, folding a leaf together to serve as a protection. The eggs of the great tropical _Bulimus_ and _Achatina_, together with those of the _Macroön_ group of _Helix_ (_Helicophanta_, _Acavus_, _Panda_) are exceedingly large, and the number laid must be decidedly less than in the smaller Pulmonata. _Bulimus oblongus_, for instance, from Barbados, lays an egg about the size of a sparrow’s (Fig. 38), _Achatina sinistrorsa_ as large as a pigeon’s. The Cingalese _Helix Waltoni_ when first hatched is about the size of a full-grown _H. hortensis_. There is, in the British Museum, a specimen of the egg of a _Bulimus_ from S. America (probably _maximus_ or _popelairanus_) which measures exactly 1¾ inch in length. The _Limnaeidae_ deposit their eggs in irregular gelatinous masses on the under side of the leaves of water-plants, and on all kinds of débris. [Illustration: FIG. 38.--Newly-hatched young and egg of _Bulimus oblongus_ Müll., Barbados. _Natural size._]