DESCRIPTION OF TWO SPECIES OF FOSSIL TURTLES, 

 TOXOCHELYS STENOPORA AND CHISTERNON? IN- 

 TERPOSITUM, THE LATTER HITHERTO UNKNOWN. 



By Oliver P. Hay, 



Of Washington, DiHtrict of Columbia. 



The thanks of the writer are due to the officers of the United States 

 National INIuseum for the opportunity to describe and iUiistrate the 

 materials which represent the two species of fossil turtles which form 

 the subject of the present paper. 



TOXOCHELYS STENOPORA Hay. 



The remains of this species which are here described were obtained 

 from Mr. C. M. Sternberg, of Lawrence, Kansas, in the Niobrara 

 beds along Butte Creek, Logan County, Kansas. 



The catalogue number in the U. S. National Museum is 6013. The 

 specimen presents a large part of the bones of a single individual, but 

 in a considerably disturbed condition. Plate 5 shows the position of 

 the various bones after the removal of the matrix that overlay them. 

 Apparently all the bones of the skull are present, but to a consider- 

 able extent separated from one another. Very few vertebra^ have 

 been preserved. The elements of the carapace have mostly been dis- 

 placed ; those of the plastron to a less extent. The pelvis is missing, 

 as well as most of the bones of the hinder limbs. 



The specimen is identified as Toxochelys stenopora^ but there are 

 not wanting some discordant characters. 



The individual was a small one. The carapace had an estimated 

 length of 160 mm. and a width of 167 mm. The width is indicated 

 by some undisturbed right and left peripherals and by the elements 

 of the plastron. The carapace is relatively broader than that of T. 

 hauri Wieland. 



The front of the skull, including the maxilla^, the vomer, the pala- 

 tines, and the prefontals, lay on the slab so as to present the palatal 

 surface (Plate 5, i). On being removed and cleared from matrix it 

 shows the nasal opening and the anterior half of the orbits. The 

 nasal opening is small, being narrow, as in the type of the species.'' 

 Its width is 5 mm., its height is 7.5 mm., but this has evidently been 



''Hay, Fossil Turtles of North America, p. 172, fig. 217. 



Proceedings U. S. National Museum, Vol. XXXVI— No. 1 665. 



191 



