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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 83 



The specimen is apparently an old individual, since most of the 

 sutures are coalesced and the outlines of the individual elements 

 can no longer be determined. The sulci outlining the dermal scutes 

 can be traced and in most instances give a clear conception of their 

 form and arrangement. The cara})ace has been badly crushed toward 

 the right side, obscuring the width of the vertebrals (pi. 17). 



The anterior border of the carapace is excavated above the neck, 

 the free border at the center of the notch being about 48 mm thick. 

 On each side of the mid line this border thins rapidly, soon form- 

 ing an acute edge that thickens again before reaching the axillary 

 notches. Behind the inguinal notches the border is slightly incom- 

 plete, but it was probably acute as in other species. 



The nuchal scute is small, as in B. sinuosa Riggs, measuring 

 34 mm long and 16 mm w^ide. The vertebral scutes, except the first 

 and fifth, are longer than wide, as showm in table 4. 



Table 4. — Measitrenients of vertebrals of Basilemys iiobilis 



The costal scutes are of large size. The second has a length 

 longitudinally of 145 mm and a height of 303 mm. They extend far 

 below the costoperipheral suture. 



The plastron is excellently preserved and at the center has a 

 greatest length of 700 mm. The sulci although relatively shallow 

 are all clearly defined, and the form and proportions of the scutal 

 areas have been certainly determined, as shown in figure 14. The 

 sutures as on the carapace are obliterated. The bridge of the plas- 

 tron measures 360 mm in width anteroposteriorly. The lobes are 

 relatively short. The anterior lobe is 318 mm wide at the base and 

 152 mm long. Its sides turn in gradually toward the median line 

 as far as the gular-intergular sulcus, from which it projects forward 

 from the rest of the curvature of the lobe, forming a wide, promi- 

 nently projecting, epiplastral beak much as in B. praeclara Ha3^ At 

 the base this beak has a greatest width of 133 mm. The greatest 

 thickness is 50 mm. 



The posterior lobe is about 118 mm long and 310 mm wide at the 

 base. The lobe appears to have been broadly rounded behind, as 

 in B. variolosa. 



