SILURIAN FOSSILS 57 



YELLOW SPRINGS . Several localities near this town, in Greene County, are good col- 

 lecting grounds. The abandoned quarry at the southeastern edge of Antioch College campus 

 exposes the Euphemia, Springfield, and Cedarville, the latter two with Pentamerus laevis . 

 The section in Yellow Springs Creek exposes the Osgood, Laurel, Euphemia, Springfield, and 

 Cedarville formations, the last three fossiliferous. 



MIAMI COUNTY. The quarry at Piqua exposes the Brassfield and the overlying Dayton 

 limestone. The Brassfield has yielded few fossils but the Dayton affords good collecting. The 

 corals Halysites , Favosites, and others are found here and several species of brachiopods. A 

 few cephalopods and gastropods may also be collected. At the north end of the quarry the sur- 

 face of the Dayton is marked by good glacial grooves. 



The Commoner Fossils 



PLANTS. A few poorly preserved impressions presumed to be seaweeds are found from 

 time to time in our Silurian rocks. In a few instances where carbonaceous layers are preserv- 

 ed the evidence of plant origin is satisfactory. 



PROTOZOA. Arenaceous Foraminifera, that is Foraminifera which built up their shell 

 with grains of sand, have been found in the Silurian rocks of Ohio. For those interested, the 

 paper by Stewart and Priddy (1941) is recommended. 



PORIFERA . Sponges and sponge -allies are not abundant enough in our Silurian rocks to 

 be described here. 



STROMATOPOROIDEA. Two genera are common in our Silurian rocks and there may be 

 others which have not yet been listed; the classification and identification of these organisms 

 is difficult. In some beds, hemispherical or globular stromatoporoids are abundant and con- 

 spicuous, so much so that they have a common name: cabbage heads. Specimens 8 and 10 

 inches in diameter are common. Some of them are silicified and weather out of the rock, roll- 

 ing down slopes or standing out prominently in the rock. The standard reference for this group 

 is Nicholson (1875). 



Forms in which there are no round bumps on the surface may be called Clathrodictyon. 

 Only one species, _C_. vesiculosum, has been recorded for Ohio; it is common in the Niagaran. 

 Forms with numerous round bumps on the surface may be referred to the genus Stromatopora 

 of which two species are common in our Niagaran. 



CONULARIDA. The surface ornamentation (fig. 80) of this group is 

 distinctive and can be recognized even in fragments. Entire specimens are 

 very scarce but the group is worth mentioning as fragments are found from 

 time to time. Conularia niagarensis has been recorded from the Brass - 

 field. 



Fig. 80 



ANTHOZOA. Corals in great variety and abundance are found in the 

 Silurian rocks of Ohio. In places, erosion has cut through reefs from 

 which corals weather out in great numbers; elsewhere, the corals are 

 closely packed in the beds as if they had lined the sea bottom in a thick mat, 

 as they sometimes do today. The following 18 genera are the commonest 



ones. Most of them can be separated by external characters but, as the following key will show, 

 some of them must be identified by internal characters. These can often be seen in natural 

 sections. Nicholson (1875) describes and figures most of our species. 



