396 Nezv York State Museum 



the plant remains found indicate Middle Devonian age. 

 They were named from Bellvale mountain in Orange 

 county. 



The Upper Devonian in New Yoi"k State has the Tully 

 limestone (Vanuxem '39) as a basal formation. It re- 

 ceives its name from the fine exposure at the town of 

 Tully in Onondaga county. As a formation this lime- 

 stone does not occur west of Canandaigua lake, but the 

 horizon beyond this to the western limits of the State 

 is marked by a thin layer of iron pyrites (one to four 

 inches) containing a dwarf fauna. In the other direc- 

 tion the formation does not extend east of the Chenango 

 river but the horizon with the characteristic fossils is 

 found as far east as Otsego county. The Tully lime- 

 stone itself carries considerable quantities of pyrites and 

 has a thickness of ten to about 30 feet. The fauna of 

 this limestone is essentially only a modification of the 

 Hamilton species. Hypothyris cuboides (Hypothyridina 

 venustula) *ihe index species of early Upper Devonic 

 time, worldwide in distribution, is present. There is 

 also the very characteristic trilobite Scutella (Bronteus) 

 tull ius. The fauna of the pyrite layer is a dwarf fauna, 

 showing arrested development due to the unfavorable con- 

 ditions under which the animals lived. However, the 

 fauna, though so diminutive, is a rich one consisting of 

 crustaceans, cephalopods, pelecypods, gastropods, brachio- 

 pods and crinoids. Corals are entirely wanting. 



The Genesee beds (Vanuxem '42) were first known 

 as the "Upper black shale" in distinction to the Marcellus 

 black shale. Then the name "Genesee shale" came into 

 use, but only for the shales between the Tully limestone 

 and the Genundewa limestone. Later the shales above s 

 and below the limestone came to be included under the 



