51 



of the strata. Homotrypa streetsvillensis is very abundant, and the lower three 

 feet are practically composed of its ramose zoaria. Homotrypa creditensis, 

 Homotrypa communis, and Homotrypa cf. richmondensis also occur but are much 

 less abundant. Numerous specimens of Stigmatella incrustans were found 

 incrusting the shells of brachiopods and pelecypods and also the zoaria of other 

 Bryozoa. Other species are: Heterotrypa simplex, Heterotrypa robusta, Stig- 

 matella interporosa, Amplexopora solitaria, Monticulipora parasitica multipora, 

 Mesotrypa patella, Hallopora aequalis, Hebertella occidentalis, Platystrophia 

 clarkesvillensis , and Zygospira modesta. 



Stromato cerium Reef. — From the 489-foot level to the 492 -foot level, 

 Stromatocerium huronense is sufficiently abundant to form a reef. Many 

 specimens measuring one foot in diameter are found. The corals Columnaria 

 alveolata, Columnaria calicina, and Tetradium approximatum, and the bryozoans 

 Heterotrypa simplex, Hallopora maculosa, and Homotrypella hospitalis peculiaris, 

 are also present. 



Zone of Bythopora meeki. — Above the Stromatocerium reef and con- 

 tinuing to the top of the member, the rocks consist of thin bands of limestone, 

 weathering to a buff colour, alternating with shale and arenaceous shale, the 

 latter showing good ripple marks. Numerous specimens of Bythopora meeki, 

 Heterotrypa simplex, Heterotrypa simplex maculosa, and Hallopora onealli credit- 

 ensis, and occasional specimens of Atactoporella densa, Homotrypella dubia, 

 Homotrypella hospitalis, Hebertella occidentalis, Batostoma cf. varians, and 

 Byssonychia grandis are found. 



Correlation. — The Streetsville member is the best-defined subdivision on the 

 Credit, 23 out of its total of 40 species being confined to it. The problem of 

 correlating it with any of the subdivisions of the typical section in Ohio has, how- 

 ever, presented some difficulties, as the fauna of the Streetsville includes elements 

 of several of the Ohio subdivisions. Before proceeding further, however, in 

 the faunal discussion, it should be explained that Shideler differs from the 

 majority of the workers on the Richmond in that he divides the Upper Liberty 

 of other authors into two parts by the Gyroceras baeri bed, calling the upper 

 part Lower Whitewater, and the lower part Upper Liberty. The Whitewater 

 of other authors thus becomes the Upper Whitewater of Shideler. On the basis 

 of Shideler's tables, we find that three Streetsville species are Upper Whitewater 

 forms: Ortonella cf. hainesi, Bellerophon cf. mohri, and Homotrypa cf. rich- 

 mondensis, while a fourth, Homotrypa streetsvillensis, a new species exceedingly 

 abundant in this formation, is very like Homotrypa austini, an Upper Whitewater 

 form. According to Shideler, four of these species listed from the Streetsville 

 range in Ohio from the Upper down into the Lower Whitewater: Ischyrodonta 

 miseneri, Byssonychia grandis, Byssonychia robusta, while a fourth, Monticulipora 

 parasitica multipora, a new variety from the Streetsville, is probably identical 

 with the form listed as Monticulipora parasitica from the same horizon in Indiana. 

 One species, Eridotrypa cf. simulatrix, ranges in Ohio from the Lower Arnheim 

 to the Lower Whitewater, and another species Stigmatella incrustans, which is 

 comparatively abundant in the Homotrypa streetsvillensis zone, is confined to 

 the Liberty in Indiana. Again, according to Shideler, three Streetsville species 

 range from lower horizons up into the Lower Liberty: Opisthoptera fissicosta, 

 Homotrypa communis, and Batostoma cf. varians. Three species are charac- 

 teristic of lower horizons than the Liberty: these are Homotrypella dubia and 

 Stigmatella interporosa, both of the Lower Arnheim, and Platystrophia clarkes- 

 villensis, of the Blanchester division of the Waynesville. The latter species, 



