76 Geological Society : — 



delicate type, like U. siibiruncatus . A Cyclas or Cyrena occurs in the 

 specimens collected by Mr. Jelly. The spiral shells are partly Palu- 

 dina, of two or pcrlmj)s three species, — one approaching in size to 

 ordinary examples of P. fluviorum, the others smaller, — and jiartly 

 of other genera. One is striated parallel to the volutions, like a 

 Littorina. Another resembles somewhat the cast of a Nalica. No 

 Cyprides have yet been recognized with certainty. Regarding two 

 of the species of molluscs above alluded to, as possibly belonging to 

 salt-water, but nil the others as due to the influence of river-action, 

 the author concludes that through a considerable part of the thick- 

 ness of these sands there is evidence now obtained of the estuarine, but 

 not lacustrine, origin of the sediments. The ujiper parts of the 

 series have been carefully explored to the summit, especially about 

 the ochre-bands, but to this date they have yielded no fossils, and 

 the author desires to leave it for further inquiry whether these 

 crowning sandstones are of the same estuary character, or belong to 

 a detached part of the Lower Greensand strata, which undoubtedly 

 exist to the south-M'cst and north-east. 



Founding his inferences on Shotover, but confirming them by re- 

 ference to ]5oints in the neighbourhood, vvbere Purbeck strata are 

 seen below these " Iron Sands," the author expresses his opinion that 

 in these sands we have a northern equivalent of the Hastings Sands, 

 — that the river to which they m.ay be ascribed was probably not 

 that of the typical Wealden, but a different stream, nourishing dif- 

 ferent Unionidcc, — and that its effects will be traced much farther to 

 the north-eastward, along the country now under survey by the 

 Government Geologis^ts, to whom is committed th.e very important 

 task of tracing the difficult boundaries of the Lower Cretaceous and 

 Upper Oolitic deposits. 



2. " On the Mineralogical and Palseontological characters of the 

 Palaeozoic Strata of the State of New York." By J. J. Bigsby. M.D., 

 F.G.S. 



In this communication the autiior presented a remmt of the chief 

 geological points characteristic of the pala;ozoic basin of New York, 

 which may thereby be compared with other districts of jialreozoic 

 rocks, 'liicse points of character and comparison were arranged 

 under the following heads : — " mineral character," " mode of trans- 

 ition from group to group of strata," " place," " position or dip," 

 " thickness," "fossils in general," "typical fossils," "fossils occur- 

 rent in Europe," and " fossils recurrent in New York." 



The evidences used in this synopsis are based upon a series of 

 elaborate tables constructed by Dr. Bigsby from the writings of 

 James Hall, Vanuxem, Conrad, De Verneuil, Murchison, Sliarpe, 

 Sowerby, Portlcck, Salter, M'Coy, Morris, and others. I'he author 

 commenced with a sketch of the geographical features of the region 

 under consideration, illustrated by the great geological map of middle 

 North-east America j)repared by himself. 



The characters of the several members of the pala;ozoic basin of 

 New York were then concisely described in succession, under the 



