168 NEW YORK STATE MUSEUM 



appear or become indeterminate, and the Oneonta sedimentation 

 is continued without interruption directly into the Catskill, the 

 entire series of beds representing there a continuance of similar 

 estuarine conditions. Organic remains in these Oneonta deposits 

 are by no means of common occurrence. Fish remains are some- 

 times found in most excellent preservation, and some of these 

 have -been described, but these nectonic animals are not neces- 

 sarily to be regarded as proper members of the fauna of this es- 

 tuarine province. Large quantities of terrestrial driftwood, often 

 forming handsome specimens of Lepidodendron and fern 

 fronds, have been brought in by the surface drainage, and over 

 the surface of the soft shales one may find traces of annelid 

 tracks, crustacean trails and impressions of ostracodes. The 

 most characteristic fossil of the entire series however i^ the 

 Cypricardites csl t s k i 1 1 e n s 1 (S , of Vanuxem, the A m- 

 nigenia catskillensis. of Hall. This large Unio-like 

 shell, showing in its form and hinge structure its relation to its 

 fresh-water descendants, abounds in some places in the Oneon'a 

 beds, particularly in the outcrops about Oxford. 



In the Clarke quarry at Oxford the principal bluestone layer 

 'is a compact, fine-grained, greenish gray sandstone lying at the 

 base of the opening, having a thickness of about 25 feet and 

 known by the quarr3aiien as " liver rock ", an expression equiva- 

 lent to tl)e better known term, freestone. Below this layer the 

 quarrymen at times expose a similar sandstone having a thick- 

 ness of about 5 feet which, though not always accessible, is 

 regarded as of excellent quality for commercial purposes. Some 

 months ago, by the favor of E. E. Davis of Norwich, my atten- 

 tion was called to the fact that this rock, which is really seldom 

 exposed, is crossed vertically by regular specimens of Ortho- 

 ceras standing with the apexes downward and traversing the 

 entire thickness of the layer. The specim.ens brought to me at that 

 time had been dislodged from the matrix and showed that the 

 shell had been replaced entirely by the sand and all its cavities 

 filled in the same way by the sediment. The cones also had been 

 more or less compressed laterally and yet preserved the evidence 



