450 AMPHIBIA ORDER ILCAUDATA. 



genera included in the sub-family now under consideration, Ranidens from 

 the north-eastern provinces of China and the east of Siberia, JSatrachyperus 

 from Tibet, and Dicamptodon from California, constitute a group character- 

 ised by the teeth on the palate forming a pair of arches, separated from one 

 another in the middle line, and with the convexity forwards. The second of 

 these genera differs from the other two in that the hind-feet are four-toed. 

 A third group is formed by the Japanese Onychodactylus, in which the palatal 

 teeth form a double arch, without any medium gap, while the claws are black. 

 In the last group, represented by the Japanese and Chinese Hynobius, and 

 Salamandrella of Eastern Siberia and Kamschatka, the palatal teeth converge 

 backwards in a somewhat V-shaped figure ; the first genus having five hind- 

 toes, and the second only four. 



The other two sub-families are small. In the first, or Plethodontince, the 

 parasphenoid bone differs from that of the two preceding sub-families in 

 bearing teeth ; the vertebrae being of the same type as in the Amblystotnatince. 

 Of the genera included, Autodax (Anaides), Plethodon, and Batrachoseps form 

 a North American group characterised by the tongue being attached along 

 the medium line as far as its front margin ; the first genus having very few 

 teeth in the jaws, while in the second the hind- toes are five in number, and 

 in the third only four. The second group, which is likewise North American, 

 although its first genus ranges into Central America and the West Indies, 

 includes Spelerpes and Manculus, and differs from the last in that the tongue 

 is attached only by a pedicle from the middle of the lower surface, so that 

 all its edges are free. 



The fourth and last sub-family, Desmognathince, is also North American, 

 and while agreeing with the third in having teeth on the parasphenoid, differs 

 in that the bodies of the vertebrae are cupped behind and convex in front. 

 In the typical genus Desmognathus the tongue is attached all along the middle 

 line, whereas in Ttiorius it has a central pedicle, and is thus mushroom-like. 

 Haptoglossa, from Costa Rica, is nearly allied to the latter, but differs in that 

 the tongue is adherent in front. Of more interest is the single species of 

 Typhlotriton, which inhabits a cave in Missouri, and is totally blind, the 

 rudimental eyes being buried beneath the continuous skin of the head. 



Although very small, the second family of the tailed amphibians is note- 

 worthy on account of containing the largest members of the entire order. 

 Most of the few species are North American, but the giant 

 Family salamander is an inhabitant of Japan and China. In their 



Amphiumidue. general structural characters the members of this family 

 agree with the Salamandridce, from which they are sharply 

 differentiated by the absence of eyelids. All of them have the bodies of the 

 vertebrae cupped at both ends, and in all the body is much elongated, and the 

 relatively small front and hind-limbs widely sundered from one another. 

 These features are clearly indicative of a closer relationship with fishes than 

 obtains in the case of the true salamanders and newts. The same affinities 

 are indicated by the aquatic habits of these creatures, and likewise by the 

 permanent retention of internal gills ; and, owing to the presence of the latter, 

 respiration can be effected without the necessity of coming to the surface, at any 

 rate for a considerable time. It is interesting to note that remains of a fossil 

 species belonging to the same genus as the giant salamander occur in the Ter- 

 tiary rocks of the Continent, from which it may be inferred that the family 

 has migrated westward. The giant salamander (Megalobatrachus maximus) 

 is a huge sluggish creature, frequently growing to as much as a yard in length. 



