143 



CHAPTER XXIY. 



PERIWINKLE OF THE ROCKS. GREEN PASTURES. — THE DOOR OF HORN. 



VARIATIONS. ' PIN-PATCHES.' LACUNA. — ASIMINEA. RISSOA, SPECIES 



AND HABITS. — JEFFREYSIA. — SKENEA. 



LITTORINIDuSl. 



The small, ratlier lively molluscs belonging to this group 

 are doubly interesting to collectors of limited opportunity, 

 seeing that some of them are to be found crawling about 

 in great numbers in almost all the places where the ocean 

 spray washes the rocky shores of Albion. Living, as their 

 name implies, between watermarks on the shore, they can 

 be seen and taken without the dredge. The typical repre- 

 sentative of the family, the well-known " Periwinkle,'' is 

 among the most familiar of our shell-fish. 



I. LiTTORiNA. — The pleasures of a sea-side ramble are 

 much increased by an intelligent observation of the varied 

 forms of animation that we meet with, among which the 



