260 



SELSEY DEPOSITS. 



terranean seas. But the two most remarkable 

 shells of this deposit are Lutraria rugosa and Pecten 

 polymorplius. 



Both of these shells are well-known forms, and 

 are exceedingly common throughout the south 

 Lusitanian zone of the Atlantic, including the 

 Mediterranean ; but they have not as yet occurred 

 further north than about Lisbon, which may be 

 taken as their limit in that direction. Both of 

 these species are good characteristics of the fauna 

 of the south Lusitanian province, and in the early 

 stage of the distribution of Atlantic fauna, they 

 were fully as characteristic of the seas in the 

 latitude of the English Channel, for the Lutraria 

 rugosa was most abundant there. The distance which 

 now separates these fossil and living forms of the 

 same species is as much as four hundred miles, a 

 distance as great, and in the same direction, as that 

 in which the living representatives of the Touraine 

 species have to be sought for. 



Clear indications of the southern character of 

 the early Atlantic marine fauna may be tracked 

 still further north, and the temptation becomes 

 oreat to dwell on the fossil contents of some of the 

 old sea-beds of Ireland, which show so clearly, and 

 for how long, that early fauna lingered on. 



The representation here made of the early condi- 

 tion of the Atlantic, and consequent character of 



