n8 



STUDIES IN THE EVOLUTION OF ANIMALS 



disposed plates on its carapace which at first sight seem a con- 

 fusion of platelets without any order ; but further investigation 

 reveals on the right side, 1 below one of the longitudinal crests, 

 the fact that several of them are disposed in distinct rosettes 



FIG. 68. (a) Bone-rosettes on the carapace of the Leathery Turtle (Dermoc/ielys coriacea) ; 

 (b] crested plate of Nile Crocodile, encircled by small plates from right flank ; (c] crested plate 

 of Sturgeon (Accipenser sturio] seen between the larger plates on the spine and flank ; all 

 from the Natural History Museum. 



exactly like those of the Glyptodon, as shown in Fig. 68 (a). 

 Curiously enough, this Turtle is one of those whose carapace is not 

 like that of other Turtles, fused with the spine and ribs. There is 

 therefore some suspicion that it may be one of the ancestral forms 

 of such mammals as the Glyptodonts, otherwise it would be strange 



1 Specimen in Natural History Museum. 



