94 



OHIO FOSSILS 



In Melocrinites the width of the cup is about equal to the 

 height; the smooth, convex plates of the cup will distinguish 

 this from Arthroacantha . M. onondaga is found in the Columbus. 



Arthroacantha is also about as wide as high; the plates of the 

 cup are not convex; they are beautifully ornamented with wart- 

 like granules. A. carpenteri (fig. 232) occurs in the Silica. 



Hexacrinites is like the first two in having about equal 

 height and width; the plates of the cup are not convex and they 

 bear no granules. _H. leai is found in the Silica. 



Dolatocrinus (fig. 233) has a bowl -shaped cup, wider than 

 high; the plates are convex, and each is ornamented with radi- 

 ating ridges. Several species are found in our Devonian. 



Euryocrinus has a deeper and smaller cup than Dolatocrinus 

 but it is still wider than high; the arms are large and branching; 

 the plates are slightly convex, smooth, and the base is conical. 

 E. laddi occurs in the Silica. 



Gilbertsocrinus has a large cup, wider than high, and bowl or vase shaped, 

 with straight sides. The plates are very convex and smooth; the base is flattened. 

 G. ohioensis (fig. 234) is found in the Silica. 



Megistocrinus is also wider than high. Its plates are smooth and'convex, 

 but less so than those of Gilbertsocrinus . Several species are found in our Dev- 

 onian. 



GRAPTOZOA . The only graptolite recorded for the Devonian of Ohio is Dictyonema le- 

 royense , found in the Columbus. It is fan shaped, branching, and has cross-bars. The colony 

 suggests the bryozoan Fenestrellina but the black color in well preserved specimens indicates 

 that it is a graptolite. 



FISHES. The Devonian of Ohio has long been famous for its fossil fishes. A few nearly 

 complete skeletons are found now and then in the Middle Devonian limestones but by far the 

 most interesting and spectacular finds have come from the Upper Devonian black shales of 

 northern Ohio. Newberry (1873, 1875, 1889) has described most of the genera and species and 

 his monographs are still usable for identification. More recent papers are by Dunkle andBun- 

 gart (1939 — 1946). 



We wish that we could pick out a few genera common enough to be worth illustrating here, 

 but it simply can't be done. In the middle Devonian bone beds fish plates, teeth, and fragments 

 are abundant enough but they are not easily identifiable. Good material has been found in the 

 Cleveland shale, in pockets that were soon worked out. If you should be fortunate enough to 

 uncover such a pocket, report your find to the nearest museum. You might be able to work 

 out your specimens yourself but it would be far better to entrust them to a specialist who will 

 be able to get full scientific value from them. See chapter 2, p. 19 for discussion of some 

 Devonian fishes. 



Books for further study 



Books on particular groups have already been noted in the text. Collectors in northwest- 

 ern Ohio should get a copy of Stewart's (1927) bulletin on the Silica shale and Ehlers, Stumm, 

 and Kesling's (1951) for descriptions of the outcrops and sections. Both of these have illustra- 

 tions of fossils. 



