12a 



Tihe Badland Formations of the Black Hill© Region 



need to refer to them in further detail here but anyone wishing 

 to continue their investigation will find an excellent help in Mr. 

 O. P. Hay's great work, "The Fossil Turtles of North America." 

 published in 1908 by the Carnegie Institute of Washington. 



Siylemys nebrascensis, the common form, was first des- 

 cribed in 1851;, by Dr. Joseph Leidy, and is the earliest dis- 

 covered fossil turtle in America (see Plate 50). The first speci- 

 mens were obtained by Dr. John Evans of the Owen Geological 

 Survey in 1849 an( ^ since then hundreds of specimens have found 

 their way into the museums of the world. The visitor in the Bad- 

 lands can scarcely fail to find them if he walks along the outcrops 

 of the containing strata and in favorable localities he may see 

 them with surprising frequency. I myself have observed many 

 dozens of them in a few hours walk in Indian draw and there 

 are other places where they seem to be as abundant. They are 

 found particularly in the Oreodon beds but occur in the 

 Protoceras beds also. As yet none have been found in the 

 Titanotherium beds. 



(c) 



Figure 19 — Head of Stylemys nebrascensis. Natural size, (a) view of 

 right side, (b) view from above, (c) view from below. After Hay, 1906. 



The shell body is often preserved with remarkable perfec- 

 tion but owing to the fact that weathering readily separates the 

 bones, specimens exposed on the surface are usually more or less 

 disintegrated. The head and feet are rarely found. Dr. Leidy, 



