Proceedings of the British Association. 117 



Good Hope ; and the Succinea oblonga has also a very wide range. The 

 consideration of the distribution of native species in foreign countries, 

 was pressed as an important part of the examination, since, without 

 such consideration, many fallacies may arise in drawing our conclusions. 



Mr. Lyell observed, there were several points in relation to the dis- 

 tribution of recent animals that geologists required to know. In the 

 first place, the influence of various kinds of rocks on the distribution 

 of species. Strata in various stages of their growth contained various 

 species. What were the laws which regulated this distribution with 

 existing species 1 The mere chemical influence of strata is important. 

 Freshwater shells exist without marine, and vice versa ; and it was de- 

 sirable to know what was the influence of rocks in their neighbourhood 

 upon them. It was desirable to know the chemical composition of 

 rocks, as in many instances this must have great influence. Mollusca, 

 for instance, formed their shells from lime, which they must have taken 

 up as food. Again, a knowledge of the distribution of subaqueous 

 species became important ; and the sediments in the beds of rivers, and 

 places where they are found, should be carefully observed and recorded ; 

 also the depth of the waters in which they are found, and the fuci or 

 other plants which may grow in their neighbourhood. Shells are the 

 most frequent organic remains, and therefore the most important. 

 Mammalia, fishes, and reptiles are frequently absent in strata, but 

 shells never. One of the great difiiculties in studying these shells, was 

 a want of knowledge of those which existed. As we passed through 

 each stratum, the shells of each resembled more and more those of the 

 strata above it, the nearer they were to it. Now the question presented 

 itself in some of the upper strata, as to whether conchologists might 

 not have overlooked existing species, and thus animals be thought 

 extinct which are not so. Mr. Bean, of Scarborough, had lately found 

 a shell that was supposed to be extinct. Another point of importance 

 is the relation of shells to each other in a given district, such as the 

 relation of the shells in rocks to those found in the sea near them. He 

 had lately proposed the question to Messrs. Gray and Sowerby, as 

 to whether there was any means of determining the relation between 

 the number of the species of shells in the Mediterranean and the seas 

 of the north of France. They told him there was no satisfactory means 

 of doing so. They differed in their estimate, and the amount of infor- 

 mation was of little value. 



Mr. J. E. Bowman exhibited specimens of a species of Dodder (Cuscu- 

 ta epilinum), first found in Britain, two years ago, by himself; and again 

 in a new locality, within the present month. He believes it is to be 

 found exclusively upon flax, and has been overlooked for C. Europcea, 

 from which, however, it is quite distinct in its pedunculated heads, glo- 

 bular tube of the corolla, and the insertion of the stamens above the 

 tips of the scales, which are geminate or bifid, with the lobes divaricate 

 or fimbriated. As he observed these scales to differ a good deal from 



