ORDERS OF AMPHIBIA. 435 



and a row of palatine teeth forms a concentric series with the 

 maxillary teeth. The tongue is fleshy, fixed to the concavity 

 of the lower jaw, and not protrusible (fig. 185). The ribs are 

 numerous, but there is no sternum. The adult possesses lungs. 

 one of which is smaller than the other, and the nose opens 

 behind into the mouth. The eyes are rudimentary, nearly 

 concealed beneath the skin, or altogether wanting. 



The position of the Ccecilitz was long doubtful ; but their 

 Amphibian character was ultimately proved by the discovery 

 that whilst the adult breathes by lungs, the young possess 

 internal branchiae, communicating with the external world by 

 a branchial aperture on each side of the neck. Only a few 

 species of Ccedlia are known, and they are all inhabitants of 

 hot climates, such as South America, Java, Ceylon, and the 

 Guinea coast. They sometimes attain a length of several feet. 



ORDER II. URODELA ( - Ichthyomorpha, Owen ; Sauro- 

 batrachia). This order is commonly spoken of collectively 

 as that of the " Tailed " Amphibians, from the fact that the 

 larval tail is always retained in the adult. The Urodela are 

 characterised by having the skin naked, and destitute of any 

 exoskeleton. The body is elongated posteriorly to form a 

 compressed or cylindrical tail, which is permanently retained 

 throughout life. The dorsal vertebrae are biconcave (amphi- 

 ccelous], or concave behind and convex in front (ppisthoc&lous], 

 and they have short ribs attached to the transverse processes. 

 The bones of the fore-arm (radius and ulna) on the one hand, 

 and those of the shank (tibia and fibula] on the other, are not 

 anchylosed to form single bones. 



In one section of the order formerly called Amphipneusta 

 the gills are retained throughout life, and the animal is there- 

 fore " perennibranchiate." In this section are the Proteus, 

 Siren, and Menobranchus. In the remaining members of the 

 order the gills disappear at maturity, and the animal is there- 

 fore " caducibranchiate." In this section are the land and 

 water salamanders. One form, however the Axolotl of 

 Mexico appears to be sometimes caducibranchiate, though 

 generally perennibranchiate. The genera Amphiuma and 

 Menopoma, also, exhibit a partially intermediate state of parts ; 

 for though they lose their branchiae when adult, they never- 

 theless retain the branchial apertures behind the head. 



Of the perennibranchiate Urodela, one of the best known is 

 the singular Proteus (Hypochthon) anguinus (fig. 186), which is 

 only found inhabiting pools in certain caves in Illyria and 

 Dalmatia. It is of a pale flesh-colour, or nearly white, with 

 three pairs of scarlet branchiae on each side of the neck. It 



