eating, huge, slow, mild, and immune from enemies, they have, apparently, 

 little need of adaptive coloration of any sort. The sea turtles, some of them 

 of almost equally great size, have decided obliterative shading, and some- 

 times — particularly on their upper shell or "carapace" — obliterative pat- 

 terns. The Hawksbill (" tortoise-shell") Turtle (Eretmochelys imbricate), 

 for instance, has, as everyone knows, a beautifully marbled carapace. This 

 pattern is obliterative, being, no doubt, a generalized sea-ground-picturing 

 pattern, like that of many fishes, crabs, etc. Kindred patterns of the cara- 

 pace are worn by certain small fresh-water and land tortoises— such as the 

 "box turtle" (Cistudo Carolina), of eastern North America. Two small fresh- 

 water tortoises of the same region are particularly notable for bright color 

 and clear pattern, namely, the common "mud turtle" or Painted Tortoise 

 (Chrysemys picta), and the little yellow-spotted brook tortoise (Clemmys 

 guttata). The Painted Tortoise has complete obliterative shading of shell, 

 head, legs, and tail, and, in addition, beautiful obliterative markings on almost 

 all his exposed skin, and on his carapace, especially along its edge. Those 

 on the top of the blackish carapace are olive green, and narrow — mere 'mar- 

 ginal bands,' bordering the plates — the rest are red and yellow, in the forms 

 of spots and broad streaks, on a dusky ground. These brighter markings 

 look like bits of rich-colored water weeds, above or below the surface, like 

 certain water and marsh flowers, like sun-flecks on the muddy bottom, and 

 like various other common details of pond and stream scenes. (Compare the 

 bill-colors of the Wood Duck, described and pictured in Chapter XI.) In 

 conjunction with the obliterative shading, and the general effect of dark water 

 and mud-color achieved by the head, legs, tails, etc., on which they occur, 

 these bright markings must often admirably serve as obliterative picture-pat- 

 terns. The under-shell or "plastron" of this turtle is immaculate light yellow- 

 buff, while a connecting shade between it and the dusky carapace is furnished 

 by the red-marked side-band of shell, and the similarly colored down-turned 

 edge of the carapace itself. The little brook tortoise (Clemmys guttata) has 

 the same general type of coloration, with many minor differences. Its bright 



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