64 ANNUAL REPORT OF 



class of vertebrates has been vastly extended, and lines of descent 

 have become revealed which afford new and precious insight 

 concerning the inter-relations of different groups. If it was pos- 

 sible for Agassiz to reconstruct accurately the entire skeleton of a 

 fish from a single scale, it is possible for us now to- treat whole 

 faunas in much the same way, since we are able to trace their 

 origin, migrations and genetic relations — in many cases at least — 

 and on bringing all these facts together, to' observe the progress 

 of evolution taking place, as it were, before our eyes. 



Contributions to our Knowledge of American Triassic Fishes. 

 — We must now turn from this imperfect survey of the scope and 

 progress of the science t0> an equally rapid consideration of the 

 work that has been done on American Triassic fishes. As early 

 as the first decades of the preceding century the pioneers of 

 American geology became interested in the fossil fishes and 

 reptilian foot-prints of the Connecticut Valley sandstone, several 

 communications in regard to them having been furnished by 

 Hitchcock, 1 Silliman, 2 Mitchell 3 and Dekay. 4 They were also^ 

 brought at an early date to' the attention of scientists abroad, 

 Brongniart, Agassiz, Lyell and Egerton having successively com- 

 mented upon them during the first half of the century. But it 

 is to the Redfields, father and son, who wrote between 1837 



1 Hitchcock, E., Discovery of Fossil Fish. Amer. Journ. Sci., vol. iii. (1821), 

 pp. 365-366. Ibid., vol. vi. (1823), p. 43. Final Report on the Geology of 

 Massachusetts, vol. ii. (1841), pp. 458-525. 



2 Silliman, B., Miscellaneous Observations, etc. Amer. Journ. Sci., vol. iii. 

 (1821), pp. 216, 365. 



3 Mitchell, S. L., Observations on the Geology of North America. 1818. 



4 Dekay, J. E., Fossil Fishes, in "Zoology of New York, or the New York 

 Fauna" (Part iv., Fishes, pp. 385-387). Albany, 1842. Also an unpublished 

 paper read before the Lyceum of Natural History of New York, noticed by 

 J. H. Redfield in the Annals of the Lyceum, vol. iv., 1848. 



The titles of these papers, with a single exception, are given by Dr. O. P. 

 Hay in his Bibliography and Catalogue of the Fossil Vertebrata of North 

 America, published in Bulletin No. 179 of the United States Geological Sur- 

 vey (1902). The exceptional paper is the posthumous report of John H. Red- 

 field, published in part by Professor Newberry in his Monograph on the Fossil 

 Fishes and Fossil Plants of the Triassic Rocks of New Jersey and the Con- 

 necticut Valley (1888). American vertebrate palaeontology properly begins 

 with the description in 1787, by President Thomas Jefferson, of mastodon re- 

 mains from Virginia, followed a few years later by descriptions of the bones 

 of Megalonyx, a gigantic sloth. 



