134 



THE EXTINCT BATRACHIA, REPTIUA 



served. The outlines of the cpisterna are not entirely demonstrable. The scale is near 

 that of the carapace preceding, but is a little too large. 



Fig. 39. 



1 



OSTEOPYGIS PLATYLOMUS plastron. 



Dermal sutures are visible in the two species whose sterna we have. Abdominal and 

 inguinal plates can be demonstrated; the anterior are not distinguishable. If anal scuta 

 exist, they must be very small, but they arc probably absent as in Cbelydra. 



Some of the Eocene Chelones have the posterior vertebral plates more dilated than in 

 the recent species, but they all present the penultimate marginals supported by a distinct 

 pair of ribs, and the anteripr marginals separate from the disc, and without rib. 



The femur of a presumed species of the- genus is more slender than in the Chelones, 

 but resembles closely that of Trionyx, while two phalanges of the same are peculiar in 

 their stout base and subterminal constriction. They arc however flattened and have 

 transverse distal condyles, being thus rather adapted for paddles than for progression, 

 thus showing the genus to have been truly aquatic. 



There appear to be remains of three species in our collections distinguished as follows : 



