Mr. R. MacAndrew on the Mqllusca of Vigo Bay. 507 



L. — On the Mollusca of Vigo Bay in the North-west of Spain, by 

 Robert MacAndrew, Esq., F.L.S., in a Letter to Professor 

 Edward Forbes, F.R.S. 



To Richard Taylor, Esq. 

 Dear Sir, May 1849. 



I SEND you a letter which I have lately received from Mr. Mac- 

 Andrew, whose zeal in the cause of natural history has induced 

 him to undertake a voyage in his yacht to Spain and Portugal, 

 with the intention of exploring the sea-coasts of those countries 

 by means of the dredge. The facts he has already brought to 

 light, as mentioned in the following letter, are of the greatest 

 interest both in a natural history and a geological point of view. 

 His discovery of an isolated littoral marine fauna (and probably 

 marine flora also) of a British or Celtic type intersecting the 

 Lusitanian province, reminding us of the boreal outliers in our 

 own seas, appears to support in an unexpected manner the theory 

 I proposed in my memoir *' On the Geological relations of the 

 existing Flora and Fauna of the British Isles,^^ published in the 

 * Memoirs of the Geological Survey of Great Britain for 1846,^ 

 wherein I maintained the former existence during the pliocene 

 and pleistocene epochs of " a geological union or close approxi- 

 mation of the west of Ireland with the north of Spain." This I 

 argued from the botanical features of Ireland and the Atlantic 

 Islands, and from the geological phsenomena which had occuiTcd 

 within the area in question since the eocene epoch. Had such a 

 connexion existed, even as by means of it we had an Asturian 

 flora transmitted northwards to Ireland, so along the coasts of 

 the same land, littoral forms of mollusca, especially during the 

 glacial period, when the tendency of conditions was to diffuse 

 northern species southwards, would in all probability have been 

 transmitted to the coasts of Spain. In no other way can we ac- 

 count for such a phsenomenon as that made known in Mr. Mac- 

 Andrew's letter. His discovery in Vigo bay of a colony of re- 

 versed Fusi, a race so characteristic of the red crag, supports this 

 view most strongly, for in the southernmost beds of the Irish 

 drift we find Fusus contrarius associated with a Spanish Mitra 

 and Purpura lapillus, in the neighbourhood of the remains of a 

 terrestrial flora of the Asturian type. 



I remain, dear Sir, very truly yours, 



Edward Forbes. 



Faro, 8th April, 1849. 

 We sailed from Portsmouth on the 9th and entered the port 

 of Vigo on the 14th ult. Being ordered to perform a quarantine 

 of ten days, we proceeded at once to the Lazaretto of St. Simon, 



