Sir H. H. Soicorth — Geological History of the Baltic. 551 



fiord Professor Miinster reported it from Smedholmen, near Brevik, in 

 a bank which reaches down to only 66 feet above the sea-level, and 

 Brogger urges that in this instance, as also in the case of Vallo, where 

 it occurs at the sea-level, the shell has probably been thrown up by 

 the waves, for it does not occur in the shell bank at Vallo nor in 

 those at Tromo by Arendal. It has also occurred at Kadland, near 

 Mandalselven, in conjunction with Ostrceaedulis, Cardium edule, Cyprina 

 islandica, Tapes decussatus, Dosinia exoleta, Nassa reticulata, Polytropa 

 lapillus, Gibbida cineraria, Turritella terebra, etc. These shells must 

 have lived in salt water and at a depth of some metres, while now 

 the bed is found with only fresh water close by and above the 

 sea-level. This, as Brogger says — and this instance is the sole one 

 from Norway — shows that My.a arenarla, while living at the close of 

 the Tapes time at the extreme south-western point of the land, 

 had not arrived there at the close of the kitchen midden time 

 (op. cit., p. 607). 



A similar discovery of Mya arenaria was also made by Jensen in 

 a raised sand beach at Nabsjert, in Vendsyssel, at a distance of 

 300 metres from the present coast and at a height of "6 metre 

 above the water. The shells measured 73 mm. in length (see Denm. 

 geol., unter., 1st raekke, p. 279, n. 3). Brogger urges that this 

 deposit dates from the same time as that at Kadland, 



Brogger adds that further east, in the Langesunds and Ghristiania 

 fiords, Mya arenaria only arrived in quite recent times (op. cit., p. 607). 

 When Lyell wrote, in 1835, it had still a limited distribution in the 

 Baltic, for he says, " This shell does not, I believe, extend so far 

 north in the Gulf of Bothnia as Sodertelje ; I could not find it even 

 at Calmar, and further south, at Solvitzborg, it was rare and of very 

 small size" (Phil. Trans., p. 10, 1835). Krajevnikof says all the 

 specimens he had himself found were young. 



Linneeus published the 10th edition of his " Systema Naturae " in 

 1768, and there described the shell, p. 670, and gave it the name it still 

 bears, and quotes as authority for it his own previous work, the 

 " Wastgoten Keisa," p. 187, which was published in 1747, and where 

 he names it Concha subarenaceo marina (under Concha he classes all 

 bivalves). This seems to show that the shell was not known to him 

 when he issued his earlier editions, and it was then probably limited 

 to the western waters of the Baltic. As a proof of its rapid diffusion 

 since, it may be well to give its present distribution in the Baltic, 

 which is thus stated by Krajevnikof (Comptes Kendus Cong. Intern. 

 Zool., Moscou, i, 151) : Eugen, Stralsund, Greifswald, Stolper, the 

 Bay of Dantzig, Calmarsund, Gotland, near Memel, Libawa, Windawa, 

 near Eiga, Dago, Oesel, Hapsal, Matzalwick, Eeval, near Narva, and 

 the Bothnian Gulf as far north as 62° 36' N. 



I have enlarged somewhat on the history of this shell in the north, 

 because it has been made a kind of test of glacial conditions in 

 England by C. Eeid and others. Thus, in the Christiania Museum 

 there are some specimens of it sent to Sars in 1866 by Crosskey 

 and Eobertson, and labelled "Mya arenaria, glacial clay, Kyles of 

 Bute." On the ticket Sars has written " glacial " with a query, 



