ACTIXEMYS MARMORATA. 469 



rior aspect of the thighs and knees, and the inferior aspect of the legs, 

 exhibit scale-like tubercles, while the rest of their surface is tuber- 

 cular; more coarsely over the thighs and legs than over the tarsi, the 

 soles, and the web; on the upper surface of the toes are large and trans- 

 verse plates. The nails, four in number, are curved and very acute. 



The tail is slender and tapering, compressed in the young and seem- 

 ingly longer than in the majority of the North American Testudmata, 

 judging of it from the illustrations accompanying the second volume 

 of the "Contributions to the Natural History of the United States 

 of America." Five longitudinal series of subquadrangular plates 

 may be observed, protecting its surface from the base to the apex, 

 although around the base, which is thicker, there are five addi- 

 tional, intervening, short, and tapering series. They are more deve- 

 loped in the transversal than in the longitudinal direction. There is 

 an upper series, exhibiting a ridge along its middle, a lateral series 

 which is smooth, as well as two inferior series. In the young, the 

 plates at the base of that organ, being rather convex or elevated, 

 assume a tubercular or nodulous appearance. 



The color assumes various shades from green to black. The speci- 

 men represented in fig. 1 is deep chestnut-brown, and that in fig. . 2, 

 light greenish above, both being reticulated with black : the black 

 lines alluded to corresponding to the rugosities of the bones beneath 

 the epidermis. The plastron is uniformly dark brown in the former, 

 and light olive in the latter, with the commissures of the scales black. 

 In the young, figured on the same plate, the upper surface of the 

 carapax is olive-brown, marmorated with black, whilst the inferior 

 surface of its projecting edge, as well as the plastron, is yellowish, with 

 black along the commissures of the scales. In some of the smallest 

 specimens, the middle region of the plastron is entirely black, a hue 

 which is gradually disappearing as the growth proceeds, at least upon 

 the specimens from Puget Sound, now before us. It appears, how- 

 ever, that in some instances, the black predominates at the exclusion 

 of any other sha'des : such appear to be the specimens which suggested 

 Emys nigra. 



The head, neck, limbs, and tail are greenish-olive, or yellow, varie- 

 gated with black ; the upper surface of the head being speckled, the 

 chin and neck lineolated, and the limbs spotted. Two narrow streaks, 

 sometimes united into a broader one, and more conspicuous than the rest, 

 are observed extending from the tympanum to the sides of the neck. 



118 



