410 Sir H. H. BoKorth—The Western Baltic. 



containing abundant fresh-water shells, among which the following 

 have been collected : Planorbis complanatiis, Bythinia tentacnlata, 

 Limncea limosa, L. ovata-normalis, Valvata cristata, V. piscinalis, and 

 an Anodonta. Below this, again, is a bed of turf a foot thick, 

 containing partly branches and partly stumps of oak-trees (Erdmann, 

 Geol. For. i Stock. Forh., i, p. 93, etc.). 



Erdmann, in the second volume of the Geol. For. i Stock. Forh., 

 gives several other instances of beds in the neighbourhood of Malmo 

 and Lund, notably at Hildesborg (a mile from Landskrona), at 

 Bjerred (a mile west of Lund), and at Barsebiick (IJ miles south- 

 east of Landskrona), where in sections, several feet thick, layers of 

 marine sand and gravel occur, containing fragments of dwarfed forms 

 of Cardium and Mya with thin shells, and lying on terrestrial deposits 

 several feet above the present Sound (vide op. cit., vol. ii, pp. 97, 98, 

 etc., etc.), all concurring to the same conclusion — that a recent 

 submergence along all this coast has been followed by a recent 

 upheaval. 



Another remarkable evidence of the submergence we are dis- 

 cussing is afforded by the Zealand river Nivaa, now a small stream, 

 but whose former course, says Rordam, can be traced at least for 

 a distance of 3 kilometres beyond the borders of the Sound, which 

 shows that here the ground had sunk to the extent at least of 

 8 metres, while on the opposite side of the Sound De Geer calculated 

 that it had once sunk 15'5 metres (Eordam, op. cit., p. 131). 



It is perfectly plain from this unanimous and most consistent 

 geological testimony that there has been a great and notable and 

 recent breakdown and submergence in various parts of the area now 

 occupied by the Danish archipelago, where it is claimed the land- 

 bridge recently existed which cut off the connection of the North 

 Sea with the Baltic. 



The breach in this connection, as we have seen, greatly affected 

 the hydrographical character of the Eastern Baltic, and especially 

 affected its molluscan and other fauna by converting what was 

 previously a fresh-water lake into a brackish sea. In pursuing this 

 induction in the previous papers, I limited my examination of the 

 lessons taught by the Baltic fauna to those presented by its eastern 

 section and to that portion of the sea lying to the east of the 

 longitude of the island of Bornholm. I now propose to examine 

 in some detail the fauna of the Western Baltic and its three great 

 waterways, and to collect some scattered facts which may be useful 

 to others besides geologists, and which greatly strengthen the case, 

 especially on its chronological side. 



I propose to begin with a conspectus or general balance-sheet of 

 the living molluscan life in the Southern Baltic, and to show its 

 accretion as we move westwards. According to Middendorf (Bull, 

 phys. Math. St. Petersb., 1850, viii, p. 65) and A. Hensche 

 (Schrift. Phys. Oec. Gesch. Konigsberg, 1861, p. 90), there are 

 only six marine shells in the eastern section of the Baltic : Hydrobia 

 halthica (Bissoa tdvce ?), Neritina fluviatilis, Mytilus edidis, Mya 

 arenaria, TelUna solidida, and Cardium edule. Of other marine 



