HAUNTS AND HABITATS 45 



themselves at such times deep down in the mud, where they 

 remain till the return of moisture. Writing of the South 

 American alligators, or caimans, the late Mr. H. W. Bates ob- 

 serves that : " Like the turtles (Podocnemis), the alligator has 

 its annual migrations, for it retreats to the interior pools and 

 flooded forests in the wet season and descends to the main river 

 in the dry season. During the months of high water, therefore, 

 scarcely a single individual is to be seen in the main river. In 

 the middle part of the Lower Amazons, where many of the 

 lakes with their communicating channels dry up in the fine 

 months, the alligator buries itself in the mud and becomes 

 dormant, sleeping till the rainy season returns. On the Upper 

 Amazons, where the dry season is never excessive, it has not 

 this habit, but is lively all the year round." 



In the preceding paragraphs it has been mentioned that 

 caimans and the great Amazonian tortoises make seasonal 

 migrations. Similar migrations are undertaken by the European 

 pond-tortoise (Emys orbicularis) when its haunts are dried up. 

 Whether under such circumstances it will aestivate, I have no 

 information. Another instance of seasonal migration among 

 reptiles is afforded by the giant tortoises of the Galapagos 

 Islands, which in the dry season make journeys into the interior 

 in search of water. It does not appear, however, that any 

 reptiles migrate south in winter in search of a warmer tempera- 

 ture : in fact their rate of progress would prevent such 

 marches. 



On the other hand, as already stated, all reptiles inhabiting 

 cold climates hibernate. The pond -tortoise, for example, buries 

 itself in mud in autumn, and does not reappear till the spring 

 is well advanced ; while some of the American terrapins burrow 

 in the banks for their winter slumber. As is well-known, the 

 South European land-tortoises kept as pets in England retire 

 for the winter months; but in their native countries the period 

 of torpor must be less prolonged. Here it may be mentioned 

 that no reptile can stand being frozen ; so that if they do not 

 burrow deep enough, such hibernating tortoises are likely to 

 perish in severe winters. 



British snakes and lizards undergo a long hibernation, retir- 

 ing in autumn, and not reappearing till spring. In the case of 

 the grass-snake it is not unusual for several individuals to occupy 



