348 



CHELONIA 



painted across. The nuchal shield is elongated and very narrow, 

 its anterior edge and that of the neighbouring marginals are finely 

 serrated. Very young individuals are at once recognised by the 

 prominent longitudinal median stripe of l)right orange extending 

 over the nuchal and neural shields ; the yellow transverse bands 

 are still absent ; they apj)ear when the longitudinal line vanishes. 

 The " Painted Terrapin " is one of the few species of whicli, 

 thanks to L. Agassiz/ complete data of growth from the new 



13UT,.!,V^^TU^ 



Fk;. 76. — Chrijsemj/s picia, "Painted Terrapin." 



Il|f|Di-T(]dr, 



born to old age are known. During tlie first six or seven years 

 the rate of growth is so uniform that numerous specimens 

 collected at the same time are readily arranged in sets of the 

 same age, simply l)y the differences they show in their size. The 

 successive lines of growth on the shields indicate the number of 

 years. After the seventh year the age is much more difficult to 

 distinguisli in those tortoises, which, like C/i. 2)icfa, have a 

 perfectly smooth epidermis. This smoothness is due to the fact 

 that the shields undergo a process of moulting. An upper, quite 

 ^ Contributions to the Xat. Hist, of the U.S.A., Boston, 1857. 



