Observations on the metamorphosis of Siredon lichenoides into Amblystoma mavortium have been made by Marsh, who also gives figures of the larval and adult forms.[[57]]
Sub-Fam. 4. Salamandrinae.–The six genera of this subfamily fall into two natural groups: I, True Salamanders, with the palatal teeth arranged in a pair of S-shaped figures, and without a fronto-squamosal arch. II, Tritons, with the palatal teeth in the shape of a Λ, i.e. the right and left series meet at an angle; the fronto-squamosal arch is present, either bony, or at least ligamentous. Triton cristatus is, however, exceptional, in that the two palatal series often do not meet and that the arch is absent. The number of fingers is universally four, that of the toes is five except in Salamandrina, which has only four.
The geographical distribution of the sub-family, entirely Periarctic, may be said to be the reverse of that of the Amblystomatinae. Of the twenty-five species namely, only two are American, four are Eastern Asiatic, and of the remaining nineteen, two are Algerian, while the rest live in Europe or in Asia Minor. It is in fact an essentially Palaearctic group.
The six genera can be distinguished as follows:–
II. The palatal teeth are arranged in two S-shaped curves. True Salamanders.
Tongue short and thick. Salamandra, p. [115].
Tongue long and projectile. Chioglossa, p. [121].
II. The palatal teeth are arranged in a Λ shape. True Tritons.
With only four toes. Salamandrina, p. [122].
With five toes.