2 24 Shell Life 



weather; but the gill-chamber holds sufficient 

 moisture to enable respiration to proceed. 



The Rough Winkle (X. riidis) has a less pointed 

 spire of from 6 to 9 whorls, of which the last whorl 

 occupies in the male one-half, and in the female 

 two-thirds of the whole ; the mouth, too, is much 

 larger in the female than in the male. The colours 

 range from white, yellow, and orange, to red, brown, 

 purple, and black, usually with spiral bands of another 

 tint, and spiral flattened ribs. The female retains her 

 eggs until they are hatched, and this is said to be the 

 reason why this species is not used for food, the 

 minute shells rendering the parent gritty and 

 dangerous to the teeth of the eater. It is every- 

 where plentiful where there are rocks and stony 

 beaches. It is half an inch across, and about five- 

 eighths in height. Experiments made by Professor 

 W. A. Herdman with this species show that it is 

 capable of living out of water for long periods. 

 Marked specimens upon the rocks were found not to 

 have moved within thirty-one consecutive days. It 

 appears to endure life in the water less than life in 

 air, and to be undergoing the change of habit from 

 sea to land that must in past 

 ages have brought about our 

 land mollusks. 



The Periwinkle or Common 

 Winkle {L. littorea) comes nearest 

 to the Rough Winkle, but differs 

 from it in being twice the size, 

 with flatter whorls, a longer 

 and sharper spire, a much slighter suture or channel 

 between the whorls ; the disproportion in size of the 



