384 MANUAL OF ZOOLOGY. 



CHAPTER LXI. 

 ORDERS OF AMPHIBIA. 



THE Amphibia are usually divided by modern writers into four 

 orders, the old order Lepidota, comprising the Lepidosiren, 

 being now placed at the head of the Fishes, under the name 

 of Dipnoi. Whilst there is a general agreement as to the 

 number and characters of the Amphibian orders, the names 

 employed to designate them are very various, and it really 

 matters little which are adopted. 



ORDER I. OPHIOMORPHA, Owen (= Gymnophiona, Huxley ; 

 Apoda of older writers: Ophidobatrachia). This is a small order, 

 including only certain snake-like, vermiform animals, which are 

 found in various tropical countries, burrowing in marshy ground, 

 something like gigantic earthworms. They form the family 

 Cczciliadce, and are characterised by their snake - like form, 

 and by having the anus placed almost at the extremity of 

 the body. The skin is quite soft, but differs from that of the 

 typical Amphibians in having small horny scales embedded in 

 it. Another fish-like character is that the vertebrse are amphi- 

 ccelous or biconcave, and the cavities formed by their apposi- 

 tion are filled with the cartilaginous or gelatinous remains of 

 the notochord. The skin is transversely wrinkled, but there 

 are no limbs. The eyes are rudimentary, and are concealed 

 beneath the skin. 



The position of the Ccecilice 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 Ccecilia 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 (== tekthyomorptia, 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- 

 coelous), or concave behind and convex in front (opistfaxahus). 



