1909.] RECENT BIOLOGY OF SOME HVIXQ SHELLS. 761 



thought it " pre-glacial " *. It is surely singular that Mya 

 arenaria should be absent from all these raised beaches in 

 England save one, as it is from all the raised beaches of 

 Scandinavia save one also, or perhaps two. 



Let us now turn to another group of raised beaches and kitchen- 

 middens, namely those in the south-west of Scotland. In his 

 account of the kitchen-midden on the coast of Ayrshire known 

 as the Ardrossan shell-mound, Mr. John Smith tells us that 

 among the shells found in it the genus Mya was entirely absent. 

 It is singular notwithstanding this that the most abundant 

 living species at the present day in this district is Mya arenaria. 

 In the lower estuary of the Gare Loch it was very abundant in 

 muddy or gravelly sand twenty yeais ago, but has been almost 

 exterminated for food by the people. (Trans. Geol. Soc. Glas. ix. 

 p. 357.) 



In the same writers account of the whale-bed in Ayrshire he 

 does not mention Mya arenaria as occurring either in the so-called 

 glacial beds at Stevenston, Kilwinning, and Troon, or in the 

 raised-beach beds at Shewalton Moor, while he says it is frequent 

 on the present beach from Stevenston to Troon [ibid. x. p. 42). 

 It is remarkable, he adds, that Mya has not turned up in the 

 raised-beach beds, although one of the species (i. e. truncata) is 

 common in the glacial beds and the other (i. e. arenaria) is 

 frequent in the estuary of Gare Loch (ibid. p. 46). 



The so-called Carse clays of the valley in which Stirling and Fal- 

 kirk lie (which prolong the Firth of Forth westwards) and in which 

 the skeletons of several whales have occurred, are probably of the 

 same age as the lower raised beaches and kitchen-middens of the 

 West Coast. Shell deposits occur in several places in these Carse 

 beds. Thus, that at Cockmalane yielded Tellina halihica (vai'. 

 soUdula), Mytilus edidis, Cardium edide, C. nodosum (?) young 

 specimen ? Buccinum undatum, Littorina litorea, of large size, 

 L. rudis, Nxicxda nucleus., Trophon truncata. Elsewhere oyster- 

 beds occur, and also Tapes p^dlastra, Mactra svbtruncata, Cardiimi 

 echinatu,7)i, Trochus cinerarius, Ptorpura lapillus, Scrobicidaria 

 piperata, Rissoa idvce, and Fusus antiquus. (" The old estuarine 

 beds of the Carse of Stirling," Haswell, Trans. Ediu. Geol. Soc. 

 xi. p. 58.) Here it will be seen there is no mention Mdiatever of 

 Mya arenaria. 



These facts make it almost certain that in the British seas, as 

 in Scandinavia, Mya arenaria is quite a recent addition to the 

 marine fauna. The fact that the shell has only quite recently been 

 reported from the Italian seas points to its having also wandered 

 very recently into the Mediterranean. These facts could not 

 well have been known to Professor Brogger, who nevertheless, in 

 trying to find the home from which the shell went to Scandinavia, 

 suggests that it had come not from Britain, but from the Atlantic 



* On its occurrence on the Thatcher Rock, see Hunt, Trans. Devon Assoc. 1888' 

 vol. XX. p. 227. The shells in the raised heach here were determined bj' Gr. Jeffreys' 

 D. Pidgeon, and J. J. Marshall ; among them is M^a arenaria. 



