1909.] RECENT BIOLOGY OF SOME LIVING SHELLS, 757 



lately spread over the English seas. The first person to write on 

 the English Mollusca in a scientific way was Dr. M. A. Lister> 

 F.R.S., who in his book entitled ' Hist. Anim. Anglise, etc.,' 

 published in 1678, was the first to mention our shell, which he 

 refere to as " concha longa lataque." He gives an excellent figure 

 of the inside of one valve showing the distinctive hinge (plate iv. 

 fig. 19), and tells us it was found in sandy ground near Philo 

 (probably Filey in Yorkshire) and very abundantly at the mouth 

 of the Tees (o/>. cit. pp. 170-171). In the series of plates of 

 English shells dated 1687, entitled 'Hist. Conch.', and apparently 

 not published till 1770, he figures two varieties of the shell, one 

 more ovate than the other (see nos. 262 and 263), and gives their 

 habitat as " Mar. Nor.," by which he meant the North Sea, and 

 it would appear that it was only as a North Sea shell that he 

 knew it. 



In his Hist. Nat. Test. Brit., published in 1778, p. 232, 

 Da Costa calls the shell Chama aretmria. He says of it : " The 

 species is not common. I have received it from the Isle of Wight, 

 near Newport, and from Hearne Ba}^, near Faversham, in Kent." 

 This points clearly to the shell being then an uncommon one in 

 the Channel. This is confirmed by the fact that it is not named 

 by Pulteney in the first edition of his ' Catalogue of Birds, Shells, 

 and Rare Plants of Dorsetshire,' published in 1799, but is men- 

 tioned and figured in that of 1813 in one of the notes, initialed 

 " T. R." (i. e. Rev. Thomas Rackell), p. 28, where he speaks of it 

 as found in Studland Bay, but says it is rare. 



It would seem, therefore, that the shell had not been a long 

 time in the Channel when these writers wrote at the end of the 

 18th century, and that theie is a certain probability that it was 

 in fact a newcomer to our seas. This is greatly strengthened 

 when we examine the most recent deposits on our coasts. 



It is almost certain that since the Christian era the land has 

 been virtually quiescent in these realms. I know of no evidence 

 to show that it has either risen or sunk during the last 2000 yeai-s. 

 The coast has been eaten back in places, estuaries have been silted 

 up and deltas enlarged, and there has been considerable alluvial 

 accession and growth of shingle-beaches, &c., in others ; but in 

 regard to any vertical change up or down, I know of no reliable 

 evidence. All the evidence, on the contrary, points the other 

 way and in favour of the level of the land having been stationary 

 since the Christian era. 



The only way. therefore, l)y which it might be possible to trace 

 any changes in the fauna of the adjoining seas during the interval 

 from the Christian era until to-day, would be an examination of 

 the estuarine deposits and grey loams or buttery clay which have 

 been deposited in such estuaries as the Wash and various inlets 

 such as those on the coasts of Essex, Hampshire, &c., correspond- 

 ing to the Cardium deposit in the now desiccated Gamborg Fiord 

 above referred to. In regard to most of these inlets the available 

 evidence is negative. The geological surveyors report no marine 



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