BIGSBY PALAEOZOIC BOCKS OF NEW YORK. 257 



, § 3. 0*1 the distribution and immediate relations of PalcBOZoic 

 Animal Life in Wales and the State of New York. — It must be pre- 

 mised that the following statements are almost whoUy based upon 

 the Tables of Palseozoic Life which accompany this memoir. In 

 Great Britain and in Europe generally, we ha^e laid under tribute the 

 accumulated labours of Murchison, Portlock, Phillips, De Yerneuil, 

 Salter, M'Coy, Sharpe, and others, — correcting the British portion 

 in accordance with the admirable catalogue of Professor Morris, a 

 work without which, in fact, these studies would have been impos- 

 sible. But I am in an especial manner bound to acknowledge 

 the invaluable assistance of Mr. J. W. Salter, Palaeontologist to the 

 Museum of Practical Geology. He has been so good as to revise 

 most carefully my Table of the mineral habitats of the Silurian 

 fauna of Wales and the adjacent English counties. So many have 

 been his corrections and additions that this Table has become more 

 truly his than mine. The Tables of the New York fossils are made 

 up principally from the writings of James Hall, of Albany, appro- 

 priately denominated by Professor Sedgwick * " the great American 

 Palaeontologist." Numerous details have also been derived from the 

 Reports of Conrad, Yanuxem, and Emmons, as well as from a recent 

 publication of James Hall, on the Brachiopoda of certain parts of 

 the United States. 



My Tables of N. American Fossils are not completely on a level 

 with the classification of the present day, and particularly in the 

 Brachiopoda, Lamellihranchiata, and Crustacea ; but I am happy in 

 thinking that their defects do not affect results. De Yerneuil and 

 Agassiz have both personally compared the rich fossil collections of 

 James Hall with his descriptions and nomenclature, and have amply 

 testified to their general correctness. The Table which distributes 

 the New York fossils into their respective sediments may be con- 

 sulted, as containing a vast preponderance of reliable facts; but 

 after all, in the sure expectation of future discoveries (not great, 

 perhaps), and in the present scarcity of chemical analyses, this 

 Table is only and simply approximate. In those rather numerous 

 cases where the American geologists have given the general mineral 

 character only, I have been guided by crystalline or other structure, 

 by the presence of animals of well-known habitats, and by other 

 collateral considerations. Ten or twelve years ago our highly 

 esteemed fellow-member the late Daniel Sharpe thought it too early 

 to obtain sound deductions from the fossils with which we were then 

 acquainted ; but since that time, the labours of Edward Forbes, Hall, 

 Barrande, Morris, and Davidson, with many others, have put a new 

 face on palaeontological science ; and after all, the question is not 

 whether these tables are perfect, but whether they furnish useful 

 truths. My persuasion is that they do : everything that care can 

 accomplish has been bestowed upon them. 



De la Beche, John Phillips, Elie de Beaumont, De Luc, Prony, and Constant 

 Prevost; to these the readei* is referred on points purposely avoided in the 

 foregoing pages. 



* Classif. Brit. Palseoz. Eocks, p. xcvii. 



