8o TORTOISES AND TURTLES. 



resemblance to an alligator surmounted by a chelonian shell. It is one of two 

 species belonging to a genus characterised by the eyes being directed upwards and 

 outwards, so that their sockets are visible in a top view of the skull ; by the tail 

 being furnished with large horny shields on its lower surface ; as well as by the 

 absence of the supramarginal shields found on the carapace of Temminck's 

 snapper. The carapace, which may attain a length of at least 20 inches, is 

 characterised by its rugose surface, bearing three well-marked tuberculated keels, 

 which tend to become smoother with advancing age ; while its vertebral shields 

 are remarkable for their great width. The snout is short and pointed, with a very 

 narrow space between the eyes ; the skin is warty, and on the chin is developed 

 into a pair of wattles or barbels. In the young the tail is as long or even longer 

 than the shell, becoming relatively shorter in the adult ; its upper surface having a 

 crest of large compressed tubercles, while the shields on the lower surface have 

 been already alluded to. As in the other members of the family, the colour is a 

 uniform olive-brown. The alligator-terrapin inhabits the rivers of North America 

 to the eastward of the Rocky Mountains, from Canada to Mexico, and is also found 

 in Ecuador. A second living species (C. rossignonii), distinguished, among other 

 features, by the presence of four wattles on the chin, is met with in Guatemala 

 and Mexico. Nearly allied to this is a third and extinct species (C. murchi- 

 soni), from the Miocene rocks of Baden ; and as we have already seen that the 

 mud-terrapins, and probably also Maw's terrapin, were represented in the Tertiary 

 strata of Europe, it is not improbable that the Eastern Hemisphere may have been 

 the original home of the present group of families. 



Temminck's Attaining considerably larger dimensions than the alligator- 



snapper, terrapin, Temminck's snapper (Macroclemmys temmincki) is dis- 

 tinguished as a genus by the lateral position of the eyes, the sockets of which are 

 invisible in a front view of the skull, as well as by the presence of three or four 

 additional or supramarginal shields on the sides of the carapace, and by the under 

 surface of the tail being covered with small scales. The triangular head is pro- 

 portionately even larger than in the alligator-terrapin, and the carapace has three 

 very strongly marked longitudinal ridges. In length, the shell may measure at 

 least a couple of feet, the tail being somewhat shorter. This species inhabits 

 North America from Western Texas to Florida, extending northwards to Missouri. 

 Since the alligator-terrapin and Temminck's snapper appear to 

 be very similar in their mode of life, their habits may be treated of 

 collectively. Both these tortoises frequent alike the rivers and larger swamps of 

 the United States, occurring in certain localities in enormous numbers, and most 

 commonly in waters that have a muddy bottom, not even disdaining the most 

 malodorous pools. As a rule, they lie in deep water, near the middle of the river 

 or swamp, although at times they show themselves on the surface, where, with 

 outstretched neck, they will float with the current. In populated districts the 

 least sound is, however, sufficient to send them at once to the bottom, although in 

 more remote regions they are less shy. At times they may be observed at 

 considerable distances from the water, probably in search of food or of suitable 

 spots to deposit their eggs. Temminck's snapper well deserves its name, since, 

 from the moment of its escape from the egg, it commences to snap and bite at 



