NEWTS AND SALAMANDERS. 445 



and pressed, one by one, into the cells in the thickened skin of his partner's 

 back, where they grow till they fit closely to the hexagonal form of their cells 

 each of which is closed above by a kind of trap-door. After some eightyl 

 two days the eggs reach their full development and produce, not tadpoles, 

 but perfect little toads. The reason of this is that tadpoles, which require to 

 breathe the air dissolved in water by means of their external gills, could not 

 exist in the cells, and, consequently, this stage of the development is passed 

 through very rapidly within the egg. "When ready to come forth, the young 

 toads, which are usually from sixty to seventy in number, although there may 

 sometimes be more than a hundred, burst open the lids of their cells, and, 

 after stretching forth their head or a limb, make their appearance. When 

 free from her charge, the mother rubs off what remains of the cells against 

 any convenient stone or plant-stem, and comes out in a new skin. After 

 breeding, these toads become much flattened, and pass the whole of their 

 time in water. 



ORDER II.— CAUDATA. 



Newts and Salamanders. 



The ordinary British newts and the black-and-yellow salamander of the 

 Continent are familiar representatives of an order of amphibians broadly 

 distinguished from the frogs and toads by the permanent retention of the tail. 

 In the skeleton they differ by the more normal structure of the bones of the 

 limbs, in which there is no elongation of any of those in the ankle joint, 

 while the ulna and fibula are respectively distinct from the radius and tibia. 

 The more typical representatives of the order are lizard-like in external form, 

 having a comparatively short body and two pairs of well-developed limbs. 

 There are, however, certain aberrant types in which the body becomes more 

 or less elongated in form, with a diminution in the size of the limbs, and in 

 some instances the disappearance of the hinder pair. From the permanent 

 retention of the tail, it is obvious that even in the more typical forms the 

 metamorphosis is a much less marked feature among these amphibians than 

 it is in the frogs and toads. And in certain instances there is no metamor- 

 phosis at all — the external gills persisting throughout life. In another case 

 we have the peculiar condition that whereas certain individuals may retain 

 their gills permanently, and breed while in this condition, other individuals 

 of the same species lose their gills, and develop into the proper adult ter- 

 restrial form before breeding. It is thus evident that these amphibians are 

 in a state of unstable equilibrium as regards their transformation ; and it 

 may be a question whether those kinds with permanent gills are not really 

 larvae, which for some reason have ceased to develop into the proper adult 

 form. 



Numerically, the tailed amphibians form a small group, containing pro- 

 bably less than one hundred and fifty species, arranged under four families. 

 They are chiefly confined to the Northern Hemisphere — where they attain 

 their maximum development in North America — and are unrepresented in 

 Australasia, the intra-tropical districts of South America and Africa south of 

 the Sahara. The true newts are, however, chiefly an Old World group. The 

 Oriental region is very poorly furnished with these amphibians, having only 



