NEWTS AND SALAMANDERS 2657 



are very abundant in the western portion of this region, but as we proceed eastward 

 they become less numerous, and we notice an approximation to American types of 

 the order, although only two genera are common to the Old and New Worlds. 

 North America is especially rich in Tailed Batrachians, containing more than half the 

 representatives of the entire suborder, and having the two-legged salamanders (Si- 

 renidce} peculiar to it. Axolotls are here especially abundant, and there are also 

 peculiar genera belonging to the families of the fish-like and gilled salamanders. 

 The Oriental region possesses only two species, namely, a peculiar genus (^Tylotri- 

 tori) of newts in Yunnan and the Eastern Himalayas, and an axolotl in Siam. Trop- 

 ical America, on the other hand, has ten species; among which may be specially 

 noticed the newts of the genus Spelerpes, which are also represented by one species 

 from Central America and the West Indies, and two others from the mountains of 

 Colombia, Ecuador, and Northern Peru. Geologically, the group is by no means 

 an old one, its earliest known representative {Hyl&obatrachus} occurring in the 

 Wealden strata of Belgium; and these animals do not appear to have become abun- 

 dant until the Tertiary epoch. 



Nearly all newts and salamanders appear to be inhabitants of water during at 

 least some period of their existence; some frequenting muddy swamps, and others 

 deep lakes or subterranean waters, while a few are found in mountain tarns at ele- 

 vations of several thousand feet above the sea. Without exception nocturnal jn 

 their habits, spending the day in slumber either concealed in hiding places on land, 

 or at the bottom of the water in their aquatic haunts, and venturing abroad only at 

 evening or after heavy rain, they are all difficult of observation, and consequently 

 much still remains to be learned with regard to their mode of life. The terrestrial 

 species generally frequent soft, shady, damp spots, but occasionally narrow valleys 

 or forests where they conceal themselves under stones or fallen trunks of trees, or in 

 holes in the earth. During their permanent or temporary sojourn in the water, the 

 adults of thos"e species unprovided with external gills are obliged to come periodic- 

 ally to the surface in order to breathe, and while in that element all are less com- 

 pletely nocturnal than when on land. Such species as are inhabitants of cold 

 regions undergo a period of torpidity during the winter months; while in tropical 

 regions others become quiescent when their haunts are dried up. They exhibit a 

 wonderful tenacity of life, and when dried up in mud, or frozen in ice, will awaken 

 at the first shower of rain, or when their icy bonds are dissolved by the sun's rays. 

 They have also the capacity of reproducing lost limbs, apparently any number of 

 times. Although on land the majority of species are slow and sluggish in their 

 movements, some salamanders from the south and west of Europe, belonging to the 

 genera Salamandrina and Chioglossa, run with the celerity of lizards; while others, 

 again, climb sloping or perpendicular faces of rocks, like geckoes. In the water all 

 swim quickly, mainly by means of serpentine movements of the tail; although the 

 water newts are perhaps the most expert swimmers. All are carnivorous in their 

 diet, feeding chiefly upon mollusks, worms, spiders, and insects. Their breeding 

 habits are peculiar in that there is usually no union between the two sexes; the fe- 

 males seizing the packets of spermatozoa deposited by the males, and conveying 

 them to their own reproductive chambers. W T hile some species lay eggs, in other 

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