I THE AMPHIBIA IN GENERAL 9 



The Plethodontinae form a large group, which is mainly 

 confined to America. The species of Plethodon, Spelerpes, 

 and Batrachoseps, the more common genera, are mostly of 

 small size. They are usually found in damp situations under 

 rocks or decaying masses of wood. A California species, 

 Autodax lugubris, has been found by Ritter 1 to have the 

 peculiar habit of laying its eggs in holes high up in the 

 branches of live-oak trees. 



The Salamandrinae are mainly found in the Old World. 

 The well-known fire salamander of Europe, Salamandra 

 maculosa, reaches a length of from six to eight inches. The 

 skin is smooth and shiny, and colored black except where 

 marked with large irregular yellow spots. The conspicuous 

 color of this species is frequently cited as an example of 

 " warning coloration," since the glands of the skin secrete a 

 substance which is very poisonous. By advertising its dis- 

 agreeable qualities in this way the Salamander is rendered 

 free from the attacks of many animals which would other- 

 wise unwittingly destroy it. Gadow tells of the dearly 

 bought experience of two American bullfrogs that were 

 kept in an inclosure with several salamanders. The next 

 morning after they were put in " the huge frogs were 

 found dead, each having swallowed a salamander, which 

 they were not acquainted with and had taken without sus- 

 picion." 



Salamandra atra is a shiny black species which lives high 

 up in the Alps. The young are retained in the uterus until 

 they attain an advanced stage of development. When they 

 are born they have no external gills, as the young of the 

 preceding species do, but these organs are nevertheless 

 fully developed in the unborn larva, in which they attain 

 a remarkable degree of development. The large size of 



1 Univ. of Calif. Publications. Zoology, Vol. 2, 1904. 



