CHAPTER XII. 



REPTILES, BATRACHIANS AND FISHES — BY A. DE C. SOWERBY. 



TN these branches of the Biological work of the Expedition comparatively 

 little was done chiefly because there was so little to collect. North China 

 is very poor in cold-blooded vertebrates and the whole collection included not 

 more than sixteen species, which were presented by Mr. Clark to the U.S. 

 National Museum. 



The explanation for this can be expressed in three words : unfavourable 

 climatic conditions. 



In the first place the excessive cold of the North China winter tells very 

 severely against snakes and lizards. For three months the thermometer 

 nightly registers from twenty to forty degrees of frost. The ground is frozen 

 hard as a rock to a depth of several feet. Rivers and lakes are covered with 

 layers of ice from two to four feet thick, whilst marshes and mountain streams 

 become solid. 



Following the severe winter frosts, comes a long period of drought lasting 

 through the spring into early summer. Sometimes this drought is prolonged 

 through the whole of the latter season. This terrible dryness is very hard on 

 batrachians, especially as it usually occurs during the spawning season, when 

 they need water most. Apart from one or two small varieties, fish do not 

 exist, except in permanent streams, rivers or lakes. 



There is little wonder then, that North China boasts so few species 

 belonging to these classes of vertebrates. As was shrewdly remarked about 

 them, they have to hibernate in winter and aestivate in summer. 



Reptiles. 



On the present expedition three species of snakes only were secured. 



The commonest of these was the olive water-snake ( Tropidomtus tigrinus), a 

 beautiful reptile of a bright sap-green colour. On the throat are patches of 

 orange red which extend down either side of the body, growing smaller till 



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