GILLED BATRACHIANS. 1 29 



rejected, and the Frog now leaps about on the land on legs 

 which have sprouted in the mean time. 150 



This remarkable metamorphosis of the higher Amphibia 

 is very instructive in its bearing on Man's ancestral history, 

 and is especially interesting owing to the fact that the 

 various groups of extant Amphibia have remained stationary 

 at various stages of their tribal history, which, in accord- 

 ance with the fundamental law of Biogeny, are reproduced 

 in this germ-history. First, there is a very low order of 

 Amphibia, the Gilled Batrachians (Sozobranchia), which, like 

 Fishes, retain their gills throughout life. To this order 

 belong, among others, the well-known blind " Olm " of the 

 Adelsberg Cave (Proteus anguineus), the Mud-eel of South 

 Carolina (Siren lacertina), and the Axolotl of Mexico (Sire- 

 don pisciformis; Plate XIII. Fig. 1). All these Gilled 

 Batrachians are fish-like animals with long tails, and in 

 point of respiratory organs and of circulation of the blood 

 they remain throughout life stationary at the Dipneusta 

 stage. They possess both gills and lungs, and can either 

 respire water through the gills or air through the lungs, as 

 occasion requires. In another order, the Salamanders, the 

 gills are lost during metamorphosis, and in the adult state air 

 only is breathed through lungs. This order bears the name 

 of Tailed Batrachians (Sozura) because they retain the tail 

 throughout life. To this order belong the common Water- 

 Newts (Triton) which swarm in all ponds during the 

 summer, and the black, yellow-speckled Land -Salamanders 

 (Salamandra) found in damp woods (Plate XIII. Fig. 2). 

 The latter are among the most remarkable of our indigenous 

 animals, sundry anatomical characters proving them to be 

 very ancient and highly conservative Vertebrates. 15 * 4 



