320 PALEONTOLOGY OF NEW-YORK. 



For these reasons, and because a careful examination of the structure of this part of the 

 country has shown a clear connexion of the rocks on the east and west si^e of the Hudson- 

 river valley, I have considered it jny duty to unite these fossils with those found in othef 

 localities of the Hudson-river group. Whatever future investigations may develope, we 

 have at present no sufficient evidence for regarding the rocks on the east side of the Hudson 

 river as distinct from those on the west side ; since they are visibly connected, and the 

 undulated and plicated structure and partial alteration commences on the west side of the 

 river, while the fossils still retain their form and unequivocal character. Those who Jh- 

 vestigate the subject should remember, also, that the discovery of a few species in the 

 altered shales on the east side of the river is not decisive of a different age of the strata, 

 while so many unequivocal forms of the unaltered rocks on the west side appear in the 

 same connexion. A careful search conducted in any part of these strata, both in the dis- 

 turbed and undisturbed regions, will lead to the discovery of many new species, which is 

 likewise true in other formations. 



I conceive, however, that it is unnecessary, in this place, to enter into detail regarding 

 the geological structure of this part of the country. This will appear in an introduction to 

 the work, with sections showing the continuation of the formations eastward, and their 

 gradual metamorphism which increases with their greater disturbance. 



