128 



OHIO FOSSILS 



23. 



a) 





b) 



24. 



a) 





b) 



25. 



a) 





b) 



26. 



a) 





b) 



27. 



a) 





b) 



28. 



a) 





b) 



29. 



a) 





b) 



30. 



a) 





b) 



31. 



a) 





b) 



32. 



a) 





b) 



33. 



a) 





b) 



34. 



a) 





b) 



35. 



a) 





b) 



36. 



a) 





b) 



37. 



a) 





b) 



38. 



a) 





b) 



39. 



a) 





b) 



40. 



a) 





b) 



Shell very smooth and shining Cionella 



Shell with distinct axial striae 24 



Shell almost cylindrical Columella 



Shell spindle-shaped Pupilla 



Shell angulated or keeled 26 



Shell with rounded whorls 28 



Shell with 3 angulations which may also be keeled Valvata 



Shell with one angulation only 27 



Surface with irregular brown markings; adult more than 



3/4 inch wide Anguispira 



Surface without irregular brown markings; adult less 



than 5/8 inch wide Discus 



Adult more than 3/4 inch wide 29 



Adult less than 3/4 inch wide 30 



Whorls increasing rapidly in size Mesomphix 



Whorls increasing slowly in size Haplotrema 



Aperture more than 1/2 the length Vitrina 



Aperture less than l/2 the length 31 



Shell globular, with flattened base Euconulus 



Shell like a thick lens 32 



Shell with 3 rows of internal lamellae Paravitrea 



Shell without internal lamellae 33 



Adult shell less than 1/8 inch wide 34 



Adult shell more than l/8 inch wide 36 



Surface with both axial and spiral ridges 35 



Surface with axial ridges only Hawaiia 



Surface with axial and spiral ridges Striatura 



Surface with axial ridges only Punctum 



Shell smooth, shining, with only a few, widely 



spaced ridges Retinella 



Shell with numerous, closely spaced ridges Zonitoides 



Shell higher than wide 38 



Shell wider than high 41 



Spire bluntly pointed Carychium 



Spire cylindrical, flat-topped 39 



Aperture widely reflected Gastrocopta 



Aperture narrowly reflected 40 



Last whorl not constricted just behind the aperture Vertigo 



Last whorl constricted just behind the aperture Pupilla 



