CIIAPTEE III 



NEOTENY REGENERATION TEMPERATURE GEOGRAPHICAL 



DISTRIBUTION 



Neoteny. — It has loug been known that the larvae of tlie Spotted 

 Salamander occasionally attain the size of 80 mm. or about o 

 inches, whilst the majority undergo metamorphosis wiien they 

 are only -iO mm. long. Again, larvae of Triton have been found, 

 in the months of April and May, 80 to 90 mm. long, still with 

 functional gills, but with the sexual organs fully developed. De 

 Filippi ^ found in one locality in Lombardy, besides a few normal 

 fully metamorphosed specimens of only 30 mm. in length, more 

 than forty sj)ecimens, which, although they had attained full 

 size, about 55 mm., and were sexually mature, still retained their 

 gills. According to him such gill-breathing, otherwise mature 

 .specimens, occur constantly in a small lake in the Val J^'ormazzo, 

 on the Italian slope of the Alps, in the province of Ossola. Later 

 Dumeril " astoni.slied the world by his account of the metamor- 

 phosis of tlie Mexican gill -breathing Axolotl into an entirely 

 lung-breathing and terrestrial creature, hitherto called AmhJij- 

 stoma, and supposed to be not only a different species, but to 

 belong to a different family from the Axolotl, which was known 

 as Siredon axolotl s. inscifmnne, and naturally classed with the 

 Perennibranchiata. 



This discovery led to a series of observations and experiments, 

 chiefly conducted by Marie von Chauvin, instigated tliereto l>y 

 Koelliker and by Caraerano." It was then found that many, 

 if not most of the European Amphibia, both Urodela and Anura, 



^ Arch. x>cr zool. epcr I'anat. ojinp., Geiiova, 1861, p. 206. 

 - Ann. sci. nat. (5), vii. 1876. 



■^ Mem. Ace. Torino, xxxv. 1883, a.w^\ Alti Ace. Torino, xvii. ISSo, ].. 81. See 

 also Woltersdortr, Zool. Garten, 1896, p. 327. 



