TAB. XIL 



Chelone crassicostata. 



View of the inner surface of the carapace, half the natural size. 



ch. The nuchal plate. 



ph . The first costal plate and adherent rib. 



ph. The second ditto. 



ph. The third ditto. 



ph. The fourth ditto. 



ph. The fifth ditto. 



ph. The sixth ditto. 



])l7. The seventh ditto. 



2)h. The eighth ditto. The figures are placed above the free projecting ends of 



the ribs ; they belong to the second and the ninth dorsal vertebrae 



inclusive. 

 sd- The ninth neural plate, 

 •s'lo. The tenth neural plate. 

 pi/. The last neural or the " pygal" plate. 



These are developed, like the nuchal plate, in the substance of the derm, 

 and do not become confluent with any parts of the endoskeleton. 



