BIGSBY ^PALiEOZOIC EOCKS OF NEW YORK. 275 



few Devonian strata in Wales. Althongh beautifully developed in 

 the south-west of England, the system has not been minutely and 

 systematically described, notwithstanding the labours of Phillips, 

 Murchison, Austen, Sharpe, and others ; we must therefore, when 

 necessary, compare the Devonian life of New York with that of the 

 Ehine as catalogued and commented upon by De Yerneuil and 

 D'Archiac (Geol. Trans. 2 ser. vol. vi.). In many phases and 

 habitudes the palasontology of the Devonian system is only that of 

 the Silurian continued, but marked by new forms and an ever- 

 increasing abundance of specific life. In 'New York, sixty-two 

 Devonian species are recurrent out of the whole 418, or nearly one- 

 seventh ; and therefore double the proportion observed in the Silurian 

 system of that basin. Thirty-eight species recur but once, twelve 

 but twice ; and the rest are scattered and few. This is as we found 

 it in the Silurian of jSTew York, and indicates that the vertical 

 range is short. Twenty-three of these recurrents are of Silurian 

 origin, — namely four from Lower Silurian, seven from Middle Silurian, 

 and ten from Upper Silurian, as is seen in Table YIII., Quart. 

 Joum. Geol. Soc. vol. xiv. p. 424. This establishes a most important 

 fact — the existence of a continuous chain of organic life from 

 one system to another in the western hemisphere. Thirty of the 

 recurrent Devonian fossils are BracMopoda ; seven are Aviculce, five 

 are Zoojphyta ; and the rest are principally Gasteropoda. In one 

 remarkable particular, the mode of recurring differs from that in the 

 Silurian strata — namely in the animal only reappearing in the nearest 

 stratum of a similar mineral character to that in which it is first 

 seen. The Corniferous Limestone and the Hamilton and Chemung 

 groups are often thus associated ; and so are Marcellus Shale and 

 Genesee Slate. Recurrence was more plentiful in the Devonian 

 system of Europe than in that of New York. As research in the 

 latter region adds to the general number of species, the probability 

 at present seems to be, that the proportion of recurrents wiQ in 

 future diminish, because the principal discoveries will lie among 

 animals either sedentary or of low vitality. I do not attempt 

 to trace the fossils of the New York Devonian into the Carboniferous 

 system of Pennsylvania, close at hand, for want of materials. An 

 examination of the valuable Catalogue of the Ehenish Devonian 

 Fossils, above referred to, presents to us some grand exhibitions of 

 the vital processes of the palaeozoic period, of comparative repose 

 for unnumbered ages, and of extraordinary longevity of species. 

 Making all allowance for occasional errors, I give my confidence to 

 the great Table of De Yerneuil and D'Archiac ; for it is mainly com- 

 piled from the labours of Phillips, Murchison, Miinster, Yon Meyer, 

 Goldfuss, and other highly esteemed observers. This Table proves 

 the connexion between the Carboniferous, Devonian, and Silurian 

 systems to have been weU-marked, and that such changes of sedi- 

 ment as were required for the sustenance of the new inhabitants did 

 not always forbid the survival of the old life. M. De Yerneuil's 

 Table proves that the Carboniferous system of Europe is connected 

 with the Lower Silurian by 4 forms, with Upper Silurian bv 13, 



