CATSKILL PERIOD. 293 



(Cypricardia angusta Con.), and a few other species, and a Euomphalus ; these, with 

 fragments of fishes, make up about all that is yet known respecting the animal 

 fossils of the beds. Among the fishes there are (fig. 509) Holojrfychius Americanus 

 (510 being a tooth of the same, and 510 a, a section of the latter) ; 511, Holo- 

 ptychius Taylori. The latter species was of large size, a portion of one of the 

 fins found in New York indicating a length of more than a foot for the entire fin. 



III. General Observations. 



Geography. — The location of the Catskill beds in eastern New 

 York instead of central or western (like the Hamilton and Che- 

 mung), and their thickness there, show that a great geographical 

 change preceded the opening of the period. The Appalachian 

 subsidence, instead of extending north over central New York, 

 involved the Hudson Eiver valley, far to the eastward ; and the 

 amount of subsidence both here and in Pennsylvania and Vir- 

 ginia was much greater than in the preceding periods. The 

 change, moreover, was attended with a complete destruction of all 

 pre-existing life, — more complete than occurred in any other part 

 of the Devonian age. Whether the Interior Continental basin was 

 an area of dry land or of water, is not clearly apparent. The most 

 probable supposition is that the great sinking of the border region 

 of the continent was attended with a rising of western New York 

 and the interior, and that the extermination of life was thus pro- 

 duced. In this event the Devonian age ended. After this, New 

 York State, excepting a border on the south, lay to the north of 

 the region undergoing progress through new formations ; for the 

 greater part of it was probably part of the dry land of the 

 growing continent. The rocks of the Coal age, with the small 

 exception alluded to, do not spread over it. Some geologists 

 would make the Devonian age close with the Chemung period ; 

 but the fossil fishes of the Catskill beds, according to Dr. New- 

 berry, appear to represent closely those of the British Old Eed Sand- 

 stone or Devonian, and no similar species have been found in the 

 Burlington or other Subcarboniferous limestones of the West. . 



If the view presented be correct, there is a bold transition from 

 the closing period of the Devonian age to the opening of the 

 Carboniferous. The former was a period in which the great Appa- 

 lachian subsidence (as in other parts of the Devonian) reached 

 north into the State of New York, while in the latter it hardly 

 passed the limits of Pennsylvania. The former was characterized 

 by dry land over the great Interior Continental basin ; the latter, 

 by a wide-spread, and clear though not deep, sea, growing Crinoids 

 and forming limestones ; for the Subcarboniferous limestone forma- 



