The pelvic arch of some of the Stegocephalia contained a well ossified pubic element, whilst in all other batrachians only the ilium, or the ilium and the ischium are ossified.
That the palatal structure must be taken into consideration by taxonomers as affording hints of some utility there can no longer be a doubt; but perhaps the characters drawn thence owed more of their worth to the extraordinary perspicuity with which they were presented by Huxley than to their own intrinsic value, and if the same power had been employed to elucidate in the same way other parts of the skeleton - say the bones of the sternal apparatus or even of the pelvic girdle - either set might have been made to appear quite as instructive and perhaps more so.
The pelvic fins are abdominal in position, long and pointed in shape, and the pelvic bones are connected with the caracoids.
In the Ecaudata the ilium is greatly elongated and the pubis and ischium are flattened, discoidal, and closely applied to their fellows by their inner surfaces; the pelvic girdle looks like a pair of tongs.
The convolutions are held together by the pelvic cellular tissue, and by involuntary muscle continuous with that of the bladder.
They resemble the latter in the elongation of the body, the large number of vertebrae (240 in Gymnotus), and the absence of pelvic fins; but they differ in all the more important characters of internal structure.
Other newts, and many salamanders, whether terrestrial or aquatic, pair, the male embracing the female about the fore limbs or in the pelvic region, and the males of such forms are invariably devoid of ornamental secondary sexual characters; but in spite of this amplexation the same mode of fecundation by means of a spermatophore is resorted to, although it may happen that the contents of the spermatophore are absorbed direct from the cloaca of the male.
In the pelvic region, from about the level of the posterior end of the ischiadic plexus, the strand of each side becomes single again, passing ventrally over the transverse processes.
The larvae are free-swimming and have the pelvic fins elongated into filaments.
The pelvic girdle and the hind-limbs show the least reduction found in any recent snakes, ilia, pubes and ischia being still distinguishable, the last even retaining their symphysis, and there are small vestiges of the femurs.