368 Reviews — Silurian Rocks of Bohemia. 



to the Lingula-flags of Britain. Stage D has the " Second Fauna," 

 and is equivalent to the Llandeilo and other beds of the Lower 

 Silurian. Lastly, Stages E, E, G, H, characterized by the "Third 

 Fauna," are Upper Silurian. M. Barrande has described the details 

 in various books and memoirs, and conspectuses of his discoveries 

 and views have been given by Murchison, Lyell, Hamilton, and 

 others. One of the most interesting points to which M. Barrande 

 has drawn attention is the occurrence of what he terms " Colonies," 

 — that is, groups of fossils having special characters, that occur in 

 thin beds intercalated in strata having a diiferent fauna, but subse- 

 quently re-occurring in higher beds as the predominant fauna. He 

 regards them as migratory and temporary off-shoots, as it were, from 

 some co-existent but distant fauna, which subsequently however 

 came into the same area in force, displacing the older fauna alto^ 

 gether. Thus, in Stage D, a thin but continuous stratum is full of 

 such fossils as are abundant only far higher up in Stage E. 



M. Barrande's earlier sections were merely diagrams ; and when 

 the Austrian Geological Surveyors examined the ground, they pro- 

 posed to draw better sections and explain the apparent difficulties. 

 MM. Lipoid and Krejgi offered therefore their views to the public, 

 suggesting that folds of the strata, obliquely and otherwise faulted, 

 would account for interventions of parts of one set of strata among 

 another ; and a discussion followed. M. Barrande's " Defence of the 

 Colonies " has been spirited, careful, and clear. In this, the third part 

 of the work, the author contrasts some of the sketch-sections of 

 Lipoid and Krej^i with sections drawn to scale, to the advantage of 

 his arguments certainly, though his pencil is not facile in rendering- 

 geological features. 



The study of the Stages G and H in the neighbourhood of HluboQcp, 

 near Prague, belongs especially to the question of the " Colonies," 

 says M. Barrande, on account of the great importance that MM. 

 Lipoid and KreJQi have attached to the stratigraphical conditions 

 (wrongly interpreted) of that locality. Therefore, these two stages 

 are now treated of in full, as to their strata and fossils, their sub- 

 divisions, and their exact relationshij) to the underlying beds that 

 contain the "Colonies" (as shown by carefully prepared sections). 

 Further, the representative strata in other countries, that centre 

 paralleled with these stages, are considered ; and lastly, the peculiar 

 occurrence in G and H of Goniatites and other fossils that are else- 

 where found, not in Silurian, but in Devonian rocks, is shown to be 

 by no means a conclusive argument in favour of their being " Devon- 

 ian." To Mr. Hamilton's admirable resume of this Memoir in his late 

 Address to the Geological Society, we may refer those who wish to 

 see an English summary of M. Barrande's observations ; we must 

 here limit ourselves to calling attention to these valuable researches, 

 so perseveringly and consistently carried on, — so well, nay, so 

 magnificently, recorded as they are in Barrande's grand work — 

 " Le Systeme Silurien de la Boheme," — and so enthusiastically and 

 successfully supported, in their generalizations, by their clear-headed, 

 untiring, and single-minded author. 



