DEVONIAN FOSSILS 75 



On some bedding planes of the Ohio shale innumerable tiny, yellowish, disk- 

 shaped objects may be found. These have been called Tasmanites ( Sporangites 

 in older publications) and are probably the spore coats of a plant otherwise unknown. 

 Large spore cases of different shape (fig. 150) from the same beds may be called 

 Foerstia. These probably represent remains of a type of marine alga. 



PROTOZOA. Foraminifera have been recorded from the bone beds of the 

 Columbus and Delaware limestones by Stewart and Lampe (1947). The bone bed FigTtib 



species are arenaceous forms, that is, forms built up of sand grains. They are all microscopic 

 in size. 



PORIFERA . Sponge spicules are fairly common in our Devonian limestones, especially 

 in the bone beds, but they are inconspicuous and not likely to attract attention. Whole sponges 

 are very rare. 



STROMATOPOROIDEA. Three genera of stromatoporoids are common in our Devonian 

 limestones, especially in the coral-bearing beds. The generic and specific characters are inter- 

 nal but some genera can be recognized in natural sections. If you have the side of a specimen, 

 wet it, and the structure will show up better. Nicholson (1875) has descriptions and figures of 

 most of our species. 



Stylodictyon can be identified because of the rather regular pillar -like structure of the cross- 

 section which is caused by the upbending of successive layers. The pillars are continuous 

 throughout most of the thickness of the colony. S. columnare is found in the Columbus limestone. 



Syringostroma has larger pillars than Stylodictyon but they are less persistent. Syringo - 

 stroma densa is recorded from the Columbus limestone. 



Stromatopora has parallel layers, without the pillars of the first two genera. Star-shaped 

 groups of radiating grooves can often be seen on the surfaces, as well as low, rounded bumps. 

 Three species are found in the Columbus limestone. 



CONULARIDA. This small group of animals, probably Hydrozoans, has been discussed 

 and figured in the Silurian chapter (fig. 80). They are rare in our Devonian rocks. 



ANTHOZOA. The Middle Devonian of Ohio has long been famous for its abundant and well 

 preserved corals. They have been described and figured by Stewart (1938) whose work should 

 be consulted for identification of species. Nicholson (1875) gave descriptions and figures of most 

 of our species also. 



Coral reefs have been cut through, either by erosion or quarrying, in many localities in 

 central and northern Ohio; many of them afford good collecting for corals. Both colonial and 

 horn corals, some of them of large size, are included in our fauna, as well as the unique "button 

 coral" ( Hadrophyllum) , really a horn coral with a very rudimentary cup. Only the commoner 

 genera are listed here. They are keyed according to external characters but, as for all fossil 

 corals, they are distinguished mainly on internal features. See Stumm (1949) for revision of 

 genera and families. 



Key to the Commoner Devonian Corals of Ohio 

 (see p. 4 for use of keys) 



1. a) Animals in colonies of many individuals 2 



b) Animals solitary > 10 



2. a) Tubes arranged in parallel masses 3 



b) Tubes arranged serially Aulopora, Ceratopora, Romingeria 



