plastral

The present specimens have carapace lengths of 250 and 238 mm. and plastral lengths of 185 and 176 mm.

Chelydra serpentina, which may occur sympatrically with C. rossignoni in some parts of Central America, has a narrower plastral bridge and only two barbels beneath the chin.

Increments in plastral length averaged 68.1 per cent in the year after hatching, 28.6 per cent in the second year and 18.1 per cent in the third year.

In the Testudinidae the African Kinixys has a movable hinge on the posterior part of the carapace and Pyxis arachnoides of Madagascar has a short, hinged, anterior plastral lobe.

The external scutellation of the plastral hinge in adults also differs from that in juveniles.