FIRST BOOK OF ZOOLOGY. 



25. In the land snails, it was learned that the eggs 

 were deposited separately, while in the air-breathing, fresh- 

 water snails the eggs were inclosed in a gelatinous substance. 

 Among the sea snails there are many species which inclose 

 their eggs in pods, or capsules, as is also the case in the oper- 

 cnlated fresh-water snails. Sometimes the capsules are 

 clustered together in large masses, as in those of the whelk 

 (Fig. 31) : 



FIG. 31. A VEKY SMALL CLUSTER OF EGGS OF THE WHELK DEPOSITED ON THE STEM OF 



A LARGE SEA- WEED. 



In others they are united in a long string (Fig. 32). 



A s E 



FIG. 32. A, a Portion of a String of Egg-Capsules, from a Florida Species of Whelk similar 

 to Fig. 27 ; B, a single Capsule separated, showing Outlet, o, through which the Young 

 escape; , Stem. 



The common cockle sticks its separate egg-capsules side 

 by i ide upon the rock (Fig. 33). 



