Newman, Habits of Tortoises. 143 



particular except that it has become highly speciaHzed in its food. 

 It is neither remarkably timid nor aggressively courageous. 

 It is very fond of basking, but cannot be accused of marked 

 sluggishness. It is active m the water and a fair traveler on land, 

 but m neither element does it equal Aspidonectes. Graptemys 

 might be chosen as a norm to w^hich other species could be referred 

 for comparison. 



^. Chrysemys marginata (the Western Painted Tortoise'). 



This species closely resembles the well-known C4irysemys picta, 

 described at some length by Agassiz. The family Emydidae, 

 to which Graptemys, Chrysemys, Nannemys, etc., belong, shows 

 a gradual advance from a purely aquatic to an almost exclusively 

 terrestrial mode of life. Graptemys is thoroughly aquatic, 

 Chrysemys less so. The other members of the family will not 

 be considered in this account. It will be of interest, however, 

 to note the tendency toward a terrestrial life displayed by 

 Chrysemys. 



Chrysemys appears a little later in the spring and hibernates a 

 little earlier in the fall than Graptemys. 



The two species are found closely associated during all of the 

 warm months, but Chrysemys is very much in the minority, 

 being only about one-tenth as numerous in Lake Maxinkuckee 

 as Graptemys. In other bodies of water in the vicinity the pro- 

 portion is reversed or in some cases Graptemys is entirely absent. 



The nesting season of Chrysemys corresponds closely to that 

 of Graptemys and the methods of hibernation, so far as I have 

 been able to observe, are identical. 



They prefer the stagnant lagoons and quiet bays to the waters 

 of the open lake and consequently are to be found basking only in 

 these places. They are often seen in company with Graptemys 

 on the ledges bordering the lagoons. It is characteristic of 

 Chrysemys to bask with the posterior portion of the carapace 

 submerged. It is not uncommon to see them basking high and 

 dry on the shores and ledges, but the other habit is more frequent. 

 This trait results in a curious growth of algae on the posterior rim 

 of the carapace in very many specimens. Those that spend long 

 periods entirely out of the water seldom show growths of algae. 

 Here we have another interesting case of individuality in habit. 



