6o NEW YORK STATE MUSEUM 



Cyathophyllum hydraulic um Simpson and Leper- 

 d i t i a a 1 1 a are reported by Clarke and Luther ^ from the Ron- 

 dout of the Tully quadrangle immediately south of Syracuse. 



Manlius limestone. The Manlius limestone or uppermost mem- 

 ber of the group carries a marine fauna which is remarkable for the 

 abundance of its individuals and the fewness of its species. Crinoids, 

 a Stromatopora and the brachiopods Spirifer vanuxemi 

 Hall and Stropheodonta varistriata (Conrad) are min- 

 gled with other, possibly pelagic, forms such as T e n t a c u 1 i t e s 

 gyracanthus Eaton, L e p e r d i t i a alta (Conrad) and .a 

 species of Beyrichia. 



This assemblage has been regarded as a " dwarf " fauna by 

 Shimer ^ who says, " The occurrence of these dwarf faunas between 

 the periods of small exceedingly dense seas or lakes, depositing salt 

 and gypsum, and the normal marine conditions of the Helderbergian 

 is an additional proof of the greater-than-normal density of the 

 water at that time." The mud-crack zones of the Manlius clearly 

 indicate that the material accumulated at no great depth and it is 

 not unlikely that the environment of a shallow fluctuating sea may 

 account, in part at least, for the peculiarly restricted life. Whatever 

 the explanation, it is obvious that the physical conditions were un- 

 favorable for the growth and development of a rich and diversified 

 marine fauna. 



The intercalations of drab waterlime which occur near the top of 

 the Manlius and which make so striking a color contrast with the 

 blue limestone, are generally believed to indicate a return of the 

 conditions which prevailed during Rondout and Salina time. This 

 view is strongly supported by Mr Luther's find of eurypterids 

 in the Manlius waterlime of Split Rock.^ 



REPRESENTATIVES OF THE HELDERBERGIAN FAUNAS 



In most sections of the limestone escarpment south of Syracuse 

 there intervene between the terminal waterlime bed of the Manlius 

 and the Devonic Oriskany sandstone, a varying number of feet of 

 limestone which carry a mixture of indigenous forms persisting from 

 the Manlius, and of exotic types strongly suggestive of the Helder- 

 bergian faunas, which attain their highest expression in the eastern 

 portion of the State. These invaders are, however, apparently 



1 N. Y. State Mus. Bui. 82, p. 38. 



2 American Naturalist, 42:481. 



3N. Y. State Mus. Bui. 69, p. 1163. 



