ART. 9 A NEW EXTINCT TURTLE FROM IDAHO — GILMORE 6 



The nuchal bone has a length of 56 mm (52 mm), a width of 

 28 mm (33 mm) in front, and an extreme width of 62.5 mm (52 mm). 

 The free border is acutely edged. The nenrals are broad, hexagonal, 

 ^vith the widest end forward. Their dimensions are given in Table 1. 

 The form of both the neurals and vertebrals is clearly shown in 

 the figures. 



The total length of the plastron (fig. 2) is 296 mm (274 mm), but 

 on the midline from the front to the apex of the posterior notch it is 

 279 mm (255 mm). The plastron is shallowly concave in front and 

 deeply notched behind. In proportions and general contour it has 



Figure 2.— Plastron of Pseudemys idahoensis, U.S.N.M. No. 12059 

 Type. One-third natural size. 



a striking resemblance to the plastron of Graptemys inornata 

 Loomis.^ The anterior lobe has a total length of 86 mm (77 mm) 

 and a width of 130 mm (122 mm). The anterior lip projects slightly 

 bej^ond the general contour of the lobe and has a width of 65 mm 

 (62 mm). Above it is shallowly spout-shaped. 



' Loomis, F. B., Amer. Journ. Sci., ser. 4, vol. 18, p. 429, figs. 10, 11, 1904. 



