86 



OHIO FOSSILS 



1. a 

 b 

 c 

 d 



2. a 

 b 



3. a 

 b 



4. a 

 b 



5. a 



b 



c 



6. a 

 b 



7. a 

 b 



8. a 

 b 



9. a 

 b 



10. a 

 b 



11. a 

 b 



12. a 

 b 



13. a 

 b 



14. a 

 b 



15. a 

 b 



Key to the Commoner Devonian Gastropods of Ohio 



( see p. 4 for use of keys ) 



Height of shell greater than its width 2 



Height and width of shell almost equal 6 



Height of shell less than its width 10 



Shell cylindrical or conical, small Pteropoda 



Aperture more than 1/3 of the height 3 



Aperture less than 1/3 of the height 5 



Shell keeled 4 



Shell not keeled, spindle-shaped Soleniscus 



Underside of shell almost flat Palaeotrochus- 



Underside of shell rounded Acanthonema 



Whorls strongly rounded, giving the spire the appearance of a 



of a string of beads Loxonema 



Whorls nearly flat Coelocaulus 



Whorls keeled or angled . . ..-.....'....' : . Murchisonia 



Whorls keeled 7 



Whorls not keeled 8 



Strongest keel at middle of whorls Bembexia 



Strongest keel near top of whorl Trepospira 



Aperture more than l/2 the height of the shell 9 



Aperture less than l/2 the height of the shell Elasmonema 



Spire very low, growth lines fine Naticopsis 



Spire high, growth lines coarse Ptychospirina 



Whorls keeled 11 



Whorls not keeled 15 



Lip free from previous whorl; shell loosely coiled Platyceras 



Lip touching previous whorl; shell tightly coiled. 12 



Spire sunken below level of whorl 13 



Spire elevated above level of whorl , 14 



Keels small, numerous, and regular, beaded, the upper 



and lower ones scalloped Porcellia 



Two strong keels only, one basal, one upper; the surface 



not beaded Pleuronotus 



Base rounded „ Mourlonia 



Base flattened Turbonopsis 



Umbilicus open Isonema 



Umbilicus closed Naticonema 



