166 



This species is quite distinct from M. geographica, as shown by the 

 much narrower alveolar surfaces of the jaws, the strongly tuberculated 

 vertebral scutes, the more distinct keel, the transverse streak behind the 

 eye, the coarser network of lines on the carapace, and the greater amount 

 of brown on the plastron. Some authors, among them recently Dr. 

 Boulenger and Prof Harry Garman (4£, xxii, 70) have given as distinct- 

 ive characters the large head of geographica and the smaller head of 

 'pseudo-geographica. The size of the head is a sexual character in both 

 species, the males having a small head, the females a large head. 

 Females of the two species of the same size have heads of approximately 

 the same width, and the same is true of the males. Of this I have satis- 

 fied myself by measurement of specimens in the National Museum and in 

 my own collection. The head is, however, variable in relative size in 

 different individuals of the same sex. Moreover, it will be found, I think, 

 that the males average considerably smaller in size than do the females. 



Habits. — This is an eminenily aquatic tortoise, spending its life in 

 rivers, lakes and ponds, and coming out of the water only to bask in the 

 sun on some rock or fallen tree, or to deposit its eggs. The food of 

 LeSueur's Map-Turtle has hitherto been regarded as animal in nature,, 

 such as small fishes, reptiles and the like, but Prof Garman states that 

 the digestive canal of most of the specimens that he observed were filled 

 with the bulbs of a sedge. In some cases, however, it was found to have 

 eaten crayfishes. The t-ggs are large, being an inch and a half in the 

 longest and an inch in the shortest diameter. According to Agassiz. 

 this species deposits its eggs earlier in the season than any others of our 

 turtles. At Natchez, Miss., one was found to have laid her eggs as early 

 as the first of June. It may here be stated that Agassiz concluded that 

 our fresh-water turtles do not lay eggs before the eleventh or fourteenth 

 year. 



This species does not appear to be employed to any considerable extent 

 as food, yet there seems to be no reason why its flesh should not be as sav- 

 ory as that of many species which are highly esteemed. 



Malaclemys geographica, (LeS.). 

 Geographic Terrapin; Map Tortoise. 



Testvdo geographica, LeSueur, 1817, 2, 86, pi. v; Emys geographica,. 

 Holbrook, 1842, 54-, i, 99, pi. xiv ; Graptemys geographica, Agassiz, 1857,^ 

 4, i, 436, pi. ii, figs. 7-9 ; Malacoclemmys geographicus, Cope, 1875, 12, 53 ;. 

 Boulenger, 1889, 84. 90; Emys lesueurii, Gray, 1831, 112, 31. 



Shell depressed, and keeled in small individuals, becoming more ele- 

 vated, higher and more rounded in full grown adults. Keel with rudi- 

 mentary tubercles, this evidence of the keel persisting even in adults. 



