296 



ZOOLOGY 



between the second and third. From the dorsal end of each of the 

 three branchial arches springs a branched external gill (hr. 1 — hr. S). 

 Very similar in its external characters is the blind, cave-dwelling 

 Proteus ; and Siren (Fig. 942) differs mainly in its elongated eel- 

 like body and in the absence of hind-limbs. All three genera are 

 perennihranchiate or persistent-gilled. 



The remaining Urodela are often called cadiocihranchiate or 

 decidiious-gilled, and furnish a complete series of transitions 

 from derotrcmatoiis forms which, while losing the gills, retain the 

 gill-clefts, to salamandrine forms in which all trace of branchiate 



Salamandra maculosa. (After Cuvier.) 



organisation disappears in the adult. In Amphiuma 

 (Fig. 943) the body is eel-like and the limbs are ex- 

 tremely small : there are no gills in the adult, but two 

 pairs of gill-openings are retained throughout life. In 

 Cry2otobra7ichus there is a single branchial aperture, 

 sometimes present on the left side only ; but, as in the 

 previously mentioned genera, four branchial arches 

 are retained. In Megalobatrachus, the Giant Sala- 

 mander of Japan and China, all trace of gill-slits 

 disappears, but two branchial arches persist. Lastly, in the 

 Salamanders, such as the spotted Salamander (Salamandra 

 maculosa, Fig. 944) of Europe, and the common British Newts 

 {Molge), the adult has no trace either of gills or gill-slits, and the 

 branchial arches are much reduced. The limbs, also, in the 

 terrestrial Salamanders, stand out from the trunk, and have the 

 soles of the feet and hands applied to the ground with the toes 

 directed forwards, so as to support the weight of the body. More- 

 over, all trace of the median fin disappears, the tail becoming 

 nearly cylindrical. 



In the Anura the body is always Frog-like, the head being 



