DEVONIAN AGE. 



281 



2. Animals. — Among animals, no Corals, Crinoids, Brachiopods, or Trilobites are yet 

 known ; the coarse character of the beds accounts for their absence. There are some 

 Lamellibranchs, such as (Fig. 561) the Modiola angusta (Cypricardia angusta Con.), and 

 a few other species, and a Euomphalus ; these, with fragments of fishes, make up about 



Fig. 561. 



Lamellibranch. — Modiola angusta. 



all that is yet known respecting the animal fossils of the beds. Among the fishes, there 

 are (Fig. 558) Iloloptychius Americanus Leidy (559 being a tooth of the same, and 559 a, 

 a section of it); 5G0, Bothriolepis Taylori Newb. {Sauripteris Taylorl H.) 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 Chemung), 

 and their thickness there, seem to show that a great geographical 

 change preceded the opening of the period. The Appalachian sub- 

 sidence, instead of extending north over central New York, involved 

 the Hudson River valley, far to the eastward; and the amount of 

 subsidence both here and in Pennsylvania and Virginia was much 

 greater than in the preceding periods. After this, New York State, 

 excepting a border on the south, lay to the north of the region under- 

 going progress through new formations : the greater part of it was 

 probably part of the dry land of the growing continent ; for the rocks 

 of the Coal age, with the small exception alluded to, do not spread 

 over it. 



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

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

 iferous. The former was a period in which the grand Appalachian 

 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 a 

 large portion of 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 formations 

 are among the most extensive in the geological series, and crinoidal 

 remains are in great profusion. 



