282 New York State Museum 



by a profusion of the horizontally spreading, tabulate 

 coral Tetradium cellulosum and related species. Inter- 

 calations of a subcrystalline dark to black limestone or of 

 oolitic or shaly, whitish-weathering limestone contain a 

 larger fauna than the dove limestone, carrying pelecy- 

 pods, gastropods, cephalopods, ostracods and trilobites. 

 Other characteristic forms than the two mentioned above 

 are the cephalopods Orthoceras recticameratum and 

 0. multicameratum, the trilobite Bathyurus extans and 

 the ostracod Leperditia fabidites. The uppermost layers 

 (maximum 15 to 20 feet) of the Lowville beds are cherty 

 beds, found to be separated from the typical beds (Low- 

 ville limestone) by an unconformity, and this portion has 

 received the name Leray limestone (Ruedemann '10) 

 from the exposures at Lerayville, Jefferson county. The 

 term is applicable to the corresponding beds in the Cham- 

 plain valley. The Watertown limestone (Ruedemann 

 '10) is the name used for the "seven-foot tier" or Black 

 River limestone of Hall ('47) and was derived from typi- 

 cal exposures at Watertown, Jefferson county. In natu- 

 ral exposures or in places where the quarry face is weath- 

 ered, the Watertown and Leray formations are readily 

 distinguished from the Lowville formation below by their 

 breaking up into small cubic blocks the size of a fist. The 

 thick-bedded, blocky-weathering beds contrast well with 

 the evenly and thinner-bedded Lowville. The Water- 

 town limestone is very hard, thick-bedded, dark bluish 

 gray or black (about nine feet, including black knotty 

 limestone above). The characteristic cephalopods for 

 which it is renowned are Gonioceras anceps, Hormoceras 

 (Actinoceras) tenuifilum, Eurystomites {Pic ctoc eras?) 

 undatus. Heads of the coral Columnaria, with numerous 

 prismatic tubes, are common. These fossils already ap- 



