In the existing Proteidea
, and in the Gymnophiona
vertebral centra are amphicoelous. In the Salamandridea
they are opisthocoelous. In Pipa
also opisthocoelous, but in other Batrachia they are, for the
most part, procoelous, but vary in different regions, some
being biconvex and some biconcave.
The first vertebra, or atlas, presents two articular cups to
the condyles of the skull, but there is no specially modified
The transverse processes may be simple, but in the Labyrinthodonts,
and in the existing Salamanders, they are divided
into two processes - an upper tubercular
, and a lower capitular
process. When the transverse process is thus divided, the
proximal end of the rib is correspondingly split into a capitular
and a tubercular process.