6 THE AMERICAN MIDLAND NATURALIST 



28. Sistrurus catenatus catenatus (Rafinesque) 



29. Crotalus horridus horridus Linne 



Subclass Synapsida 

 Order Testudinata 

 Family Kinosternidae 



30. Sternotherus odoratus (Latreille) 



Family Chelydridae 



31. Chelydra serpentina (Linne) 



Family Testudinidae 



32. Clemmys guttata (Schneider) 



33. Emys blandingii (Holbrook) 



34. Terrapene Carolina (Linne) 



35. Graptemys geographica (Le Sueur) 



36. Chrysemys bellii marginata Agassiz 



37. Pseudemys scripta troostii (Holbrook) 



Family Trionychidae 



38. Amyda mutica (Le Sueur) 



39. A myda spinifera (Le Sueur) 



In all probability it will be remarked that the writer has been too con- 

 servative in preparing the above list, and that he has been too critical in his 

 treatment of the records appearing in the literature. Every area of any size 

 in which biological work has been done, however, possesses a collection of 

 records which are doubtful and which many revisers do not have the courage 

 to discard. Many unfortunately are based upon misidentifications and others 

 upon obvious escapes. Reptiles, particularly turtles, are being transported con- 

 stantly by human agency, and such extraneous species as the horned toads, 

 Phrynosoma cornutum and P. solar e, the bull snake, Pituophis sayi sayi, the 

 python, Python molurus bivittatus, the alligator, Alligator mississipiensis, and 

 the tortoise, Gopherus agassizii, etc., were collected in Ohio and reported to 

 the writer during the course of the present survey. 



It has been the policy to discount all records concerning which there appears 

 to be the least doubt. It is fully realized, of course, that the amount of field 

 work done in the state, while fairly extensive, falls far short of making avail- 

 able a complete understanding of the reptiles of Ohio, and it is expected that 

 other species will be added to the list from time to time. Likewise some of 

 the species here considered as doubtful may be shown by new material to be 

 actually a part of the Ohio fauna. It is recognized that it is much more diffi- 

 cult to prove a species does not occur in a certain area than to prove it does. 



Doubtful Records and Possible Additions 



In the discussion immediately followmg, a list of species is presented which are not 

 included m the main hsting of Ohio reptiles In this are oiven many records which 

 the writer considers doubtful. Mention also is made of species known to occur in 

 adjacent states and which eventually may be found in Ohio. The list follows: 



