72 GUIDE TO KEPTILES AND AMPHIBIANS. 



There are three British species. They all have five hind-toes, but 

 in the genus Salamandrince these are reduced to four. 



The Slimy Salamander {Plethodon glutinosus) is the type of a 

 sub-family (Plethodontince) of which all the members except the Sar- 

 dinian Salamander {Spelerpes fuscw, 554) are American. They are 

 characterised by the transverse arrangement of the palatal teeth, and 

 the presence of teeth-bearing plates on the parasphenoid, or basal 

 bone of the hinder part of the skull. In Spelerpes (with five hind- 

 toes) and Manculus (with four) the tongue is attached only by a 

 central stem ; in the other three genera it is fixed along the whole 

 middle line, and cannot be protruded. Of these latter, Anaides is 

 peculiar in the small number and large size of its teeth ; Batra- 

 choseps, in addition to its slender form, differs from Plethodon in 

 having four, in place of five hind-toes. Many of the species of 

 Spelerpes lay their eggs under stones, in water : but those of Anaides 

 are deposited in the crevices of the bark of trees, where the adult 

 Salamanders also dwell, and the young are born in an advanced state. 



Two remarkable North American Salamanders (the Mud-eel, 

 Siren lacertina, 565? fig- 73, and Pseudobranchus striatus) constitute a 

 family (Sirenidce) characterised by the retention of three pairs of 

 fringed gills, the eel-like form, the absence of hind-limbs, and the 

 short fore-limbs, which are either three- or four-toed. The eyes 

 have no lids, but shine through the transparent skin. Curiously 

 enough, the external gills of the young shrivel up, but are re- 

 developed later. In the adult Pseudobranchus the gills are covered 

 Avith skin, so as to be useless. Siren is found in ditches and ponds, 

 where it burrows in the banks, but is said to occasionally leave the 

 water. When swimming, the limbs are closely pressed to the body, 

 movement being effected by the tail. 



The typical representative of the family Proteidce is the Olm 

 {Proteus cmguinus, 564, fig. 72) of the subterranean waters of 

 Carniola, Carinthia, and Dalmatia, which is carnivorous and lives in 

 total darkness. Three pairs of fringed external gills persist through- 

 out life ; and there are three front and two hind-toes. The eyes 

 are buried beneath the opaque skin, which turns black after long 

 exposure to light. 



The subterranean waters of Texas are the home of a very similar 

 creature {Typhlomolge rathbuni), with longer limbs, of which the front 

 pair has four and the hind pair five toes. 



The ancestral type from which both the above are derived is 

 doubtless represented by the North American Four-toed Salamander 



