MEDINAN, NIAGARAN, AND CHESTER FOSSILS 
73 
shale. Beneath the Brassfield limestone there are about 4 feet 
of argillaceous material weathering into a gritty clay. The latter 
has recently been traversed by ditches, and numerous gastero- 
poda, of strongly Ordovician aspect, have been exposed. In 
addition there is a species of Ctenodonta and of one Spyroceras, 
both of which have Ordovician affinities. The brachiopoda, 
on the contrary, are distinctly Silurian in character, and the 
same is true of one fragment of a pygidium of Dalmanites. The 
list includes the following: 
1. Schuchertella siibplana brevior Var. nov. 
2. Brachy prion 
jj- Whitfieldella cf. ovoides Savage 
4. Bellerophon centervillensis Sp. nov. 
5. Hormotoma trilineata Sp. nov. 
6. Hormotoma centervillensis Sp. nov. 
7. Liospira (?) depressum Sp. nov. 
8. Lophospira ehlersi Sp. nov. 
9. Lophospira (Ruedemannia ?) centervillensis Sp. nov. 
10. Loxoceras husseyi Sp. nov. 
11. Spyroceras microtextile Sp. nov. 
12. Ctenodonta cf. simiilatrix Ulrich 
13. Dalmanites 
The specimens are not found in situ but occur intimately 
mixed together in the material thrown out from the ditch, and 
this material occurs in the original low ridges formed at the time 
these ditches were dug. Any effort to discover any other source 
is futile. 
Since the Edgewood limestone in southern Illinois and eastern 
Missouri occurs below the Brassfield limestone of those states, 
the fauna of the Edgewood limestone, as described and figured by 
Savage^^ was searched for possible similar species, but with 
no definite success. Such genera as Schuchertella, Brachy prion, 
Whitfieldella, Bellerophon, Hormotoma, Liospira, Lophospira, 
Ctenodonta, and Dalmanites are represented in the Edgewood 
limestone, and although none of the species from the Center- 
Savage, T. E., Stratigraphy and paleontology of the Alexandrian series in 
Illinois and Missouri: Illinois State Geol. Surv. Bull. 23, 1913. 
