76 THE DIFFERENCES BETWEEN 
the description of the lutter which foUows would lead 
us to infer that the color was here different (it is said to 
1)6 ''yellowish, marbled with blackish"). In young of 
both turtles the latter description is applicable, for they 
are then marbled beneath. For adnlts the description of M. 
geographicus with reference to this point is right, for both 
species are when mature of a ding}' yelloAv color beneath, 
the marbling having been gradnully lf)st during growth. 
The remainder of the description, "carapace strongly 
notched behind and usually decidedly keeled," applies to 
both species. 
COLOR. 
The ground colors and the pattern of coloration are very 
similar in the two species compared stage for stage. The}" 
agree almost line for line and spot for spot. Thus, while 
a casual look at the dorsal sides of the heads of two young, 
one of each species, seems to show that M. geograpliicii^ 
has more yellow lines on this part of the head ; close look- 
ing shows that with several conspicuous lines on the head 
of M. lesueuri are others more obscure, and that in reality 
the lines are nearly the same in number and position as in 
the related species. 
The mark which will in most cases serve to distinguish 
M. lesueuri from M. geographicus is a yellow, connna- 
shaped spot behind each eye. Each spot begins near the 
posterior border of the eye, in line with the nostril, ex- 
tends inward, sometimes a little forward, then turns pos- 
teriorly still nearing the middle line and growing narrower 
and, finally, })assing into a yellow line which extends pos- 
teriorly on the neck. Sometimes one or both of the spots 
are detached from the neck line. In some cases instead 
of curving uniformly towards the middle line the spots 
may be a trifle expanded and angulated opposite the dor- 
