494 BULLETIN 58 UNITED STATES NATIONAL MUSEUM. 



depth being considerabl}" less than half the length of carapace and 

 but slightly more than half its width; carapace with a single, median, 

 undulating keel; shields with deepl}' cut concentric lines toward 

 the border, the vertebrals and costals with well-marked bosses from 

 which issue radiating lines; nuchal rather large, almost as broad as 

 long; first vertebral slightly Avider than the others, which are as broad 

 as or broader than the adjacent costals, and all much broader than 

 long; edge of marginals from third to eighth turned up, behind the 

 latter each marginal extending considerably beyond the next with 

 its posterior corner, so that the outline is strongly serrate ; eighth and 

 ninth marginals broadest; plastron flat, angularly notched behind, 

 obtusely emarginate in front, bridge angle gently rounded, each 

 shield with deeply cut parallel lines mostly along the anterior and 

 interior margins; posterior lobe fully as long as the bridge, as wide 

 as the opening of the shell; abdominal seam much the longest, 

 longer than that of humerals and gulars together, femoral seam 

 longer than anal; inguinal shield somewhat larger than axillary; 

 toes webbed to the tips; tail rather long, more than one-third the 

 length of the carapace, tip rather blunt, base studded with numerous 

 high conical tubercles or blunt spines. Color (in alcohol) : Carapace 

 tawny-oliye, obscurely spotted ^\ith dusky; dorsal keel burnt umber, 

 this color spreading sidewise on the transverse seams of the vertebrals; 

 costals paler buff toward the outer margin, the dusk}^ or blackish 

 maculations being more distinct on this pale belt ; underside imi- 

 formly black; head above uniform olive; a narrow black line from 

 nostril to e3^e, and a narrow, pale, black-edged supratemporal band 

 from the posteriory corner of eye; neck olive gray with numerous 

 raised, slightly tuberculated longitudinal ridges which appear to be 

 paler; legs and feet blackish, with a pale band along the inner edge 

 of forearm and tibia; tail with obscure, pale, longitudinal bands, one 

 on each side of the median line. 



Dimensions. 



mm. 



Greatest length of carapace 124 



Greatest width of carapace 88 



Greatest length of plastron 117 



Length of hind lobe of plastroa 45 



Width of hind lobe of plastro i 60 



Width of bridge 1 42 



Depth of shell 47 



Width of head 19 



Length of tail from ve.. I 45 



The advlt is more elongate in proportion to widtli and depth than 

 the one described above. The male difl'ers but slightly from the 

 female, the plastron being scarcely concave, but the hind lobe of the 

 plastron is slightly narrower and the depth of the shell somewhat 



