290 C. SCHUCHERT — MEDINA AND CATARACT FORMATIONS 



c-{-CamarotOdchia neglecta (Hall) ? Specimen in American Museum. Oc- 

 curs also in Cataract and Niagaran. 



c*Whitfieldella ohlata (Hall), 1852. Lockport. Closely related to Clinton 

 forms. 

 Pelecypoda : 



Q*Pterinea (?) primigenia (Conrad), 1839. Medina. Syn. Cypricardia 

 alata Hall, 1852 : 11. 



*Pterinea, n. sp. Related to last species. Lockport and Medina. 



Q*Modiolopsis (?) orthonota (Conrad), 1839. Medina. 

 Gastropoda : 



*Pleurotomaria (?) pcrvetusta (Conrad), 1839. Medina. 



*Liospira (?) litorea (Hall), 1852. Lockport. 



*Liospira, n. sp. Much higher spire. Medina. American Museum. 



*Holopea (?) conoidea (Hall), 1852. Lockport. 



Q-\-Bucanopsis trilohata (Conrad), 1839. Medina. Also in Cataract and 

 Clinton. 

 Cephalopoda : 



XOrthoceras multiseptum Hall, 1852. Lockport. 



XOncoceras giblosum Hall, 1852. Lockport. 

 Osteacoda: 



c*Isochilina cylindrica (Hall). Medina. 



RELATIONS OF THE CATARACT TO OTHER 8ILURIC FAUNAS 



Species of the Cataract fauna. — The Cataract fauna so far as deter- 

 mined has about 76 species, but when all of the material so far collected 

 is worked up the number will certainly exceed 100 forms. Enough is now 

 known, however, to indicate clearly the relationships of this early Siluric 

 fauna. 



Relation to the Medina. — In common with the Medina, the Cataract 

 has 7 species, and when one notes that the latter is essentially a lime- 

 stone fauna and the former one of sands, the stratigraphic significance 

 of these figures is apparent. However, it will be better to reverse the 

 statement, and say that of the 22 forms constituting the Medina biota, 7 

 are also found in the Cataract. These are (1) Scolithus verticalis, (2) 

 Whitfieldella ohlata (not yet established), (3) Camarotcechia neglecta, 

 (4) Modiolopsis (?) orthonota, (5) Pterinea (?) primigenia, (6) Buca^ 

 nopsis trilohata, and (7) Tsochilina cylindrica. These fossils show that 

 the two formations are probably nearly of one time, although species 1, 3, 

 and 6 have little stratigraphic value. The guide fossils restricted to the 

 Medina are (1) Dcedalus archimedes, (2) Arthrophycus alleghaniense, 

 (3) Lingula cuneata, (4) Pleurotomaria (?) pervetusta, and (5) Holo- 

 pea conoidea. We may state the evidence in another way by saying that 

 the Medina biota has 22 forms, and of these 6 have no stratigraphic sig- 

 nificance. This leaves 16 species, of which 7 are also in the Cataract, 7 



