238 AMADEUS W. GRABAU 
The Clinton of the best known section, that of western New York, 
begins with the true or Upper Medina, which, along the Niagara 
River, admits of a number of subdivisions, which are, however, of 
only local significance.t The total thickness is nearly 125 feet, 
with 25 feet of white quartzose sandstone (Whirlpool sandstone) 
at the base, and about 8 feet of a similar sandstone at the top. The 
middle series consists of red sandstones and green and gray sandstones 
and shales. The red sandstones generally show aeolian cross- 
bedding and appear to have accumulated above water. The green 
sandstones and shales are fossiliferous. The white Whirlpool 
sandstone exhibits beach features,? and probably marks the advance 
of the sea, though it is likely that the sand was originally dune sand, 
as suggested by A. W. G. Wilson. 
The fossils aré generally most abundant in the shales and thin- 
bedded sandstones. The heavy-bedded sands are either free from 
fossils or have only scattered shells of Lingulae. At Lockport and 
elsewhere some layers are crowded with gastropod shells. The 
characteristic fossil, Arthrophycus harlani is everywhere in New York 
restricted to the upper beds just below the upper white sandstone. 
The fossils so far obtained from the Medina are: Arthrophycus 
harlani Conr.; A. sp.; Daedalus several species; Scolithes verticalis 
Hall; Dictyolithes beckii (Conr.); ‘“Fucoides” auriformis and “F.” 
heterophylius; Holo pea fragilis Hall; Lingula cuneta Conr.; Whitfield- 
ella oblata; Camarotoechia sp.; Uncinulus stricklandi (Sowerby) ; Plect- 
orthis medinaensis sp. nov.; Rhipidomella sp.; Pentamerus sp.; 
Modiolopsis orthonota; M. primigenius; Pterinea cj. emacerata; 
Pleurotomaria pervetusta Conr.; P. littorea Hall; Holopea (?) 
conridea; Bucanopsis trilobaius (Conr.); Oncoceras  gibbosum; 
Orthoceras sp.;.O. multiseptum Hall; Ascidaspis sp.; Dalmanites 
sp.; Isochilina cylindrica Hall. 
This is a Lower Siluric fauna, and favors more especially the 
Clinton and Rochester faunas. It is so far known only from western 
New York, with the exception of Arthrophycus harlani, which is 
widely distributed. In western New York this species occurs at the 
top of a heavy-bedded unfossiliferous sandstone with an aeolian type 
t See Bull. 45, New York State Museum, pp. 88-95. 
2 Fairchild, H. L., Amer. Geol., Vol. XXVIII, rgo09. 
