﻿26 



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- 

 culated fresh-water snails. Sometimes the capsules are 

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

 (Fig. 31) : 



Fig. 81. — A veey 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. 82). 



A s B 



Fig. S2.— ^, a Portion of a Strinsr of E^rg-Capsules. from a Florida Species of Whelk similsr 

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

 escape; s, Stena. 



The common cockle sticks its separate egg-capsules side 

 by side upon the rock (Fig. 33). 



