VERTEBRATA. 193 



are sharp and recurved, and there is a short fleshy tongue. 

 Prom the little that is known, the gills appear to be sometimes 

 external, sometimes internal. 



These animals, often several feet in length, burrow beneath 

 the soil in tropical countries and occasionally take to the water ; 

 they live, it is believed, on vegetable matter. 



There is only one family : 



Cceciliida. 



Siphonops. Epicrium. 



Ehinatrema. Caecilia. 



Order II. UKODELA. 



QBADIEUTIA. ICHTIIYOMORPIIA. SOZURA. CAUDATA. 

 SAUROBATKACHIA, 



Tailed amphibians with lizard-like bodies ; the caudal ver- 

 tebrae numerous and distinct. Two or four feet. Gills either 

 retained through life [perennibranchiate] or disappearing at 

 maturity [caducibranchiate]. 



The skin is always soft and naked, occasionally warty, and 

 sometimes prolonged on the back into the appearance of a fin. 

 The mouth is furnished with numerous small teeth and a short 

 tongue. The branchial openings disappear with the gills. The 

 ribs are short or rudimentary. 



The axolotl (Siredon) is the larval state of Arnblystoma ; but 

 it sometimes remains in that state throughout life, and is at the 

 same time most prolific, whilst those which must be supposed to 

 have attained a higher form are utterly sterile, the sexual organs 

 becoming apparently atrophied. From the observations of Du- 

 meril, the gills appear to be readily reproduced when lost. 



The Urodela are unknown in the southern hemisphere beyond 

 the tropic ; they are most numerous in North America. In this 

 country we have only three species, which are known as efts or 

 newts, the commonest being Triton punctatus. In the limestone 

 grottoes of Carniola is found the curious Proteus anguinus. A 

 Japanese species, Cryptobranchus maximus, attains a length of 

 six feet. The mud-eels of North America belong to the genus 

 Siren ; some of these attain a length of three feet. 



Two divisions are usually adopted Ichthyodea (three pairs 

 of gills, external or internal, and amphico?lous vertebrae), and 

 Salamandrina (without gills or gill-openings, and opisthoccelous 







