I20 The Irish Naturalist. May, 



is probabl}^ the most remarkable feature of the notes on 

 ** solid " geolog)^ Oldha^nia itself, now known from several 

 parts of the world, is so t3'pically a Cambrian organism that 

 the argument should, it seems to us, have been turned round 

 the other way. Frankl}^ there is so far not a shred of evidence 

 for regarding these beds as Upper Silurian, although such 

 strata might reasonably be expected in the chain. If Mr. 

 M'Henry's reading of the sequence is correct, the so-called 

 Lower Silurians are most probably not Upper Silurian, but 

 Lower Cambrian. Mr. Lamplugh's wise comparison of the 

 system of rocks here displayed with the Skiddaw Slate (p- 8), 

 points out the lines on which research must now go forward. 

 In any case, the supposed unconformitj' between the Bray 

 series and the '*' Lower Silurian " is at present made of no 

 account. Here is a point that shows how much scope there 

 is for revision of a wide area, if such work can ever again be 

 undertaken. 



Mr. Lamplugh introduces several interesting and trenchant 

 paragraphs into the account of the Carboniferous Limestone, 

 notably in regard to " knoll-structure " (pp. 9 and 78), Mr. 

 Seymour's contributions to petrograph}^ (pp. 21-27) are 

 similarl}^ welcome, and owe scarcel}^ anything to the previous 

 edition of the Memoir. We notice that he uses " Lov/er 

 Silurian " freely for the shales, while in some other sections 

 the term has been cautiously excised. 



Mr. Lamplugh then gives " a general account of the glacial 

 and post-glacial deposits " (pp 36-54), to which readers on both 

 sides of the Irish Sea will turn. The terms used for the 

 divisions of the drift are clearl}^ explained, and attention is 

 called to the '' dry gaps," such as the Dingle, as having had a 

 glacial origin. We are glad to note (p. 40) that the classifi- 

 cation of the drift as Lower Boulder Clay, Middle Sand and 

 Gravel, and Upper Boulder Clay, is no longer maintained, 

 except as a purely local feature. Strong evidence is adduced 

 to prove that the famous shell-bearing gravels have been 

 placed in their present positions by glacier-ice ; and a 

 coincident epoch of submergence is not admitted. This 

 argument is elaborated later (pp. 114-115) in the case of the 

 Kill-of-the-Grange clay, but is distinctly weakened by the 

 suggestion that the materials of that formation, including 



