TESTUDINIDAE 



349 



transparent layer of each shield peels off completely like a piece 

 of mica. I have been able to confirm Agassiz' statement on Ch. 

 concinna in their third and fourth springs, and on a number of 

 adult Ch. picta. The latter were not allowed to hibernate, being 

 kept in a warm tank ; they peeled completely during the late 

 autumn, and then the red and yellow colours underlying the 

 newly formed shields appeared very vividly ; others moult at 

 midsummer. 



Growth of Ch. picto,, after Agassiz. 



The size of the eggs varies considerably, from 26 by 17 to 30 

 by 16 millimeters; sometimes they are perfectly round, 17 mm. 

 in diameter. 



Ch. concinna. The specific character by which this Terrapin 

 may be easily recognised is a pair of orange - red broad 

 streaks, which extend from above the eye to the sides of the 

 neck. The general colour is olive-brown above, variegated with 

 yellowish dark - edged lines, which, together with numerous 

 rugosities, radiate from the middle field of each shield. The 

 plastron is yellow, often with blackish symmetrical patches, and 

 sometimes these become confluent and preponderant. Very young 

 specimens are extremely pretty, the ground-colour of the carapace 

 being green, each shield with darker, somewhat concentric 

 markings, most conspicuous and regular on the upper surface of 

 the marginals, where the marks of the adjoining shields form 

 one pattern-system across the dividing lines. The plastron is 

 either uniform yellow or has a few pairs of blackish spots 



