NO. 9 NEW YORK POTSDAM-HOYT FAUNA 255 



The facies of the fauna is essentially Cambrian, with the possible 

 exception of the gastropods Matherella saratogcnsis, Eccyliopicrus 

 sp., Ophileta ? sp., and Sinuopea ? sp. These, however, are all small 

 forms and might well be the Cambrian progenitors of the Ozark 

 gastropod fauna of Missouri. Dr. E. O. Ulrich has recently placed 

 the " Saratogan " fauna far above the top of the Cambrian ^ but with 

 the evidence now known to me from New York and the Appalachian 

 region to the southwest I am inclined tentatively to refer the fauna 

 as found in New York State to the upper limit of the Cambrian. This 

 is subject to mvestigations now being made in the Upper Mississippi 

 Valley region of Wisconsin and Minnesota that will probably deter- 

 mine more definitely the horizon of some of the upper faunas that 

 have been referred to the " St. Croix sandstone." As now known, 

 the " Saratogan " fauna would be correlated with the fauna of one 

 of the upper horizons of the " St. Croix sandstone " and thus included 

 in the Upper Cambrian. 



The most recent expression of opinion on the stratigraphic horizon 

 of the Potsdam sandstone in New York is by Mr. William J. Miller 

 in 1911.^ He includes it with the Theresa formation and the Little 

 Falls dolomite in the Upper Cambrian and states that the dolomite 

 was everywhere eroded prior to the deposition of the Tribes Hill 

 limestone, a formation which is frequently absent, and that the Black 

 River-Trenton limestone (generally the Lowville) rests upon an 

 eroded surface of the dolomite. 



In Dutchess County, New York,^ the " Saratogan " fauna is repre- 

 sented by Lingidella prima, Lingidella (Lingulepis) acuminata, 

 Agraulos saratogcnsis, and Lonchocephalus calcifcrns. 



Near Blairstown, New Jersey,* the fauna in the horizon of the 

 " Kittatinny " limestone there exposed has Agraulos cf. saratogcnsis 

 and Lonchocephalus cf. calciferus of the Hoyt limestone " Sarato- 

 gan " fauna. The frontal limb of the Saratoga specimen of Agraulos 

 is more convex than the one from Blairstown, and the Lonchocephalus 

 is identified by a fragment of the occipital segment and median spine. 

 Both identifications are too uncertain to be of value in correlation. 

 The species of Dicellocephalus, D. nczvtonensis Weller, is unlike the 

 Hoyt Hmestone species D. hartti Walcott. It is similar to the Diccllo- 



^ Bull. Geol. Soc. America, Vol. 22, 1911, No. 3, pi. 27: Table of formations. 



■ Bull. New York State Museum, No. 153, Geology of the Broadalbein 

 Quadrangle, 191 1, pp. 25-31. 



^ New York State Museum, Geology of the Poughkeepsie Quadrangle, C. E. 

 Gordon, 191 1, p. 49. 



* Geol. Surv. New Jersey, Rept. on Pal., Vol. 3, 1903, p. 13. 



