EMYDID^E. 



359 



The total length of" the plastron (fig. 456) is 272 mm.; but along the midline, from the 

 front of the plastron to the bottom of the posterior notch, the length is about 265 mm. The 

 anterior lobe has a length of about 85 mm. and a width of 140 mm. At the suture between the 

 epiplastrals and the hyoplastra the width is 122 mm., and this width is continued backward 

 about 22 mm. further. The entoplastron is 51 mm. wide. The anterior lip projects somewhat 

 and has a width of 60 mm. 



The posterior lobe has a width of 134 mm. and a total length of 90 mm. Toward the hinder 

 extremity the lobe narrows rather rapidly and is posteriorly deeply notcht. The humero- 

 pectoral sulcus passes behind the entoplastron. The gulars extend along the midline for 



455- 



^_^ -^^v^^*- 



FIGS. 455 AND 456. Graptemys tnornata. Carapace and plastron of type. X about }. 

 455. Carapace. 45&. Plastron. 



47mm.; the numerals, 29 mm.; the pectorals, 30 mm.; the abdominals, 63 mm.; the temorals, 

 53mm.; the anals, 30 mm. The bridges have a width of 100 mm. 



The present species is here referred with doubt to the genus Graptemys Agassiz. It can 

 hardly belong to the genus Chrysemys as that is here defined and the type of which is C. picta. 

 The shell of this White River species has some resemblance to that of Graptemys geografhica, 

 having a low rounded dorsal carina and an elongated first suprapygal, like the living species 

 just named. The species may belong to either Pseudemys or Trachemys; but it will be neces- 

 sary to have the skull in order to determine its relationships with certainty. 



Genus TERRAPENE Merrem. 



Shell usually short and broad, rarely elongated. Neural bones hexagonal, with the broader 

 end forward. The eighth neural usually absent. Plastron as broad as the opening of the 

 carapace, composed of two distinct portions movable on each other and the carapace, there 

 being a ligamentous hinge between the hyoplastra and the hypoplastra and another on each 

 side between the bones mentioned and the carapace. Zygomatic arch complete, deficient, or 

 wanting. Alveolar surfaces of the jaws narrow and without ridges. Choanae between fronts 

 of orbits. Digits with little or no web. Tail short. 



Type: Terrapene Carolina (Linn). 



The known members of this genus are confined to North America. The species are 

 closely related, and their number is not certainly determined. On the number of the digits 

 of the hinder feet and the condition of the zygomatic arch the genus has been, especially by 



