Fauna in Columbia Co., Neiv York. 411 



decreases downwards, carrying the typical Oriskany species 

 into the Dalmanites dentatus layers and below, and making 

 the whole series of this group at Port Jervis probably over 

 two hundred feet in thickness, of which one hundred or more 

 belong to the Lower Oriskany. The relations of these beds to 

 the Oriskany was appreciated by Barrett," who was led, how- 

 ever, to refer them to the Lower Helderberg on account of the 

 occurrence of some doubtful Lower Helderberg species and 

 their stratigraphical position. 



In the paper on Becraft's Mountain by W. M. Davis, f the 

 Upper Pentamerus, including the Scutella limestone, is stated 

 to have a thickness of from forty to fifty feet, followed directly 

 by the Cauda-galli shales. At Pondout, he recognized a re- 

 currence of the Shaly limestone above the Scutella beds. The 

 same conditions obtain at Becraft's Mountain, and at the top 

 occur the few feet of cherty and arenaceous beds containing 

 the Lower Oriskany fossils. 



The paleontological aspect of this fauna is of much interest, 

 especially on account of the large number of genera and spe- 

 cies new to the Oriskany group and species new to science. 

 Even the forms which are characteristic of the Oriskany 

 sandstone above offer slight variations in size and features 

 which enable them to be recognized as from a somewhat older 

 horizon. As a whole, the fauna is transitional. A few of the 

 Lower Helderberg types lingered ; others were changed into 

 species intermediate between Lower Helderberg and true 

 Oriskany and Cornif erous forms ; and new types also appeared, 

 which in the higher rocks reached a greater development. 

 Among some of the new types of structure may be mentioned 

 the coarsely plicate Leptoccelia, the Spirifers with plications in 

 the sinus and the Corycephalus group of Dalmanites, having 

 the outer margin of the cephalon denticulate. c. E. B. 



II. 



A preliminary List of the Species constituting the Oriskany 

 fauna of Becraft's Mt., JV. Y. 



(Names in roman are of species present in the normal Oriskany or Hipparionyx 

 fauna of Central New York and the Schoharie Section ; for convenience of reference 

 the letters H and D are placed before names of species belonging respectively to 

 Lower Helderberg and upper-Lower, or Middle Devonian types.) 



Fishks. 1. Spine of undetermined species. 



Axnklids 2 Spirorbis sp. 



(D) 3. Autodeius sp n. This genus is also represented in the Hamilton shales, 

 but by a much larger species. 



* Ann. Lyceum Nat. Hist. N. Y., vol. xi, p. 297, 1876. 

 f This Journal, III, vol. xxvi, pp. 381-389, Nov., 1883. 



