THE GEOGRAPHIC TURTLES. 79 



as distinctly so as in the other species. In the adult they 

 are quite black and are larger. On each dorsal plate is a 

 pair of black dots, sometimes more. At the sutures be- 

 tween adjacent costal plates are dark blotches, but they are 

 smaller and less distinct than in the other species. Blotch- 

 es at the sutures between marginals are also present. 



The plastron of young M. geographicus is, as a whole, 

 paler than that of M. lesueuri. The black of this region 

 is not in this species so closely aggregated nor so exten- 

 sive. In some examples it forms about a dozen isolated 

 spots, each with concentric lines of pale yellow alternat- 

 ing with the black. In other examples the black occupies 

 most of the plastron, but the yellow areas within it give 

 the effect of a yellow plastron marbled with black. In 

 adults of both species the plastron is dingy yellow in col- 

 or, sometimes with a trace of the dusky spots, but in large 

 examples without any trace of the pattern which is so con- 

 spicuous in the young. 



Apart from the features which have been mentioned, the 

 two species resemble one another closely in color. The 

 general color of the shell, body, head and limbs, the re- 

 ticulation of the carapace, and the pattern in limbs and 

 body furnish no ready means of distinguishing the spe- 

 cies. 



FORM AND PROPORTION. 



Iii examples of young and adults which were measured, 

 the depth of the shell was about the same for the two spe- 

 cies. An average of the depth of four examples of each 

 species, the two sets corresponding very closely as to size 

 of individuals, showed M. geographicus to be a trifle 

 deeper. 



But a more uniform convexity of the carapace of M. 

 lesueuri conveys the impression of a deeper turtle. Ow- 

 ing to this roundness of the carapace the length along the 



