886 OHIO BIOLOGICAL SURVEY 



Di Spherical or elongately oval. 



El Surface smooth or finely punctuate. 

 Fi Surface smooth. 



Qi Shell not provided with mi- 

 nute perforations. . 1. T. volvocina 

 G2 Shell provided with minute 



perforations. . . 2. T. perforate 



Fi Shell finely punctured. . 3. T. intermedia 

 E2 Surface with wart-like processes, 

 with folds, or with numerous minute 

 compact rod-like protuberances. 

 Fi Surface with wart-like process. 4. T. verrucosa 

 F~ Surface with folds or minute rod- 

 like protuberances. 

 G^ Surface covered with folds. 

 Hi Folds short, not reaching 

 from anterior to poste- 

 rior end. 



11 Folds minute, diago- 



nal. . . 5. T. rugulosa 



12 Folds, large irregu- 



lar. . 6. T. vermiculosa 



H^ Folds elongate, reach- 

 ing from anterior to 

 posterior end. . 7. T. stokesiana 



G- Surface with numerous rod- 

 like projections. 

 Hi Opening for flagellum 

 ^ ■ without a collar. . 8. T. spiculifera 



H= Opening for flagellum 



with a collar. . 9. T. vestita 



D2 Transversely oval. . . • 10. T. bernardi 



C2 Form elongately ovoid or cylindrical, the length 

 approximately 2 times the diameter. 

 Di Form oval or ovoid, not cylindrical. 

 E^ Form that of a regular oval. 



Fi Shell smooth. 



G^ Opening for flagellum ap- 

 proximately V2 the diame- 

 ter of the shell; length 

 25/" 11. T. teres 



G^ Opening for flagellum less 

 than Vs the diameter of the 

 shell; length 13-16m. . 12. T. oblonga 



F2 Shell covered with granulations 

 or punctuations. 

 Gi Collar distinct. . . 13. T. crebea 



