ICHTHYOPSIDA. 251 
are retained throughout life, and they are the main organs of 
respiration. The fore-limbs are present, but the hinder pair of 
limbs is never developed. 
The “ caducibranchiate” section of this order is characterised 
by the fact that both pairs of limbs are always developed, and 
the branchize are never retained throughout life. The most 
familiar examples are the Water-salamanders or Newts (772#o7), 
and the Land-salamanders. The Newts (fig. 135), are well 
known as inhabiting pools in our own country, and the young 
lead a strictly aquatic life. When the lungs are developed the 
external gills wholly disappear, and the respiration becomes 
strictly aerial, though the animals still spend a great part of 
their time in the water. The larva or young form is at first 
destitute of limbs, and the fore-limbs are the first to be 
developed, the reverse of this taking place in the Frogs, In 
Fig. 135.—The great Water-Newt (7 vrcton cristatus), male. (After Bell.) 
accordance with their mode of life, the tail is compressed and 
flattened, so as to form an efficient swimming apparatus. The 
Water-salamanders are all oviparous, and the young are like 
the tadpoles of the common frog. 
The Land-salamanders, in both their adult and young state, 
live upon land, and the tail is rounded and cylindrical. The 
young are not developed in water, but are retained within the 
body of the parent for a longer or shorter period, so that the re- 
production becomes ovo-viviparous, or even viviparous. There 
are no Land-salamanders in this country, but they occur upon 
the Continent, and one species lives upon high mountains. 
It is important to remember in connection with all these 
“tailed” Amphibians, that they are wholly distinct from the 
true Lzzards, with which they are often confounded. Many of 
them are completely lizard-like in form, having a long tail and 
