GASTEROPODA. 



251 



witlim the influence of fresli water, and frequently become dis- 

 torted ; similar monstrosities are found in the Norwich crao-. 



Fig. 104, Littorina littorea. (Warington.) 



The common species [L, littorea) is oviparous ; it inhabits the 

 lowest zones of sea-^weed between tide-marks. An allied species 



r, rostrum or muzzle. 

 k, buccal mass. 

 g, nervous ganglia 



(reproductive orifice, on 



the right side). 

 s, salivary gland. 

 £E, oesophagus, 

 I, lingual coH. 

 ■m, shell-muscle. 



b, branchia or gill, 



c, heart. 

 n, aorta. 



e, stomach. 



/, liver. 



h, biliarj'- canal. 



t, intestine. 



a, anus. 



o, ovary. 



d, oviduct. 

 u, uterus. 



o', ovarian orifice. 

 X, renal organ. 

 y, muctis gland. 



Fig. 105. Littorina IMof alls $ '. (after Sotileyet). Animal removed from its shell; 

 branchial cavity and back laid open. 



(X. rudis) frequents a higher region, where it is scarcely reached 

 ])y the tide * it is viviparous, and the young have a hard shell 



