570 CARBONIFEROUS LABYRINTHODONT 
into capitular and tubercular processes of nearly equal length, and 
possess a distinct ‘angle, whence a process is given off upwards and 
outwards.! In the hinder ribs the tuberculum becomes a little shorter 
and more slender than the capitulum. In Plewrodeles Waltliz, the 
vertebral column and the proximal ends of the ribs resemble those of 
Salamandra maculosa, though the division of the transverse processes 
is less marked, and the capitulum and the tuberculum of the ribs are 
not so deeply separated ; indeed, posteriorly, the separating cleft 
becomes almost obsolete. In Auproctes the division of the transverse 
processes is hardly discernible ; nevertheless there is a rudiment of the 
angular processes in the anterior ribs. In other Sawrobatrachia, a 
groove on each side, indicating an incipient division of the proximal 
end of the rib, is not uncommon. In all these cases I am not aware 
that the single or bifid character of the transverse processes is 
correlated with any notable differences in other parts of the 
organization. 
It appears to me, then, that the characters of the certainly 
Labyrinthodont vertebra ? made known by von Meyer and Plieninger, 
and in the present paper, are in perfect accordance with the view 
originally put forward by Professor Owen, that these animals are more 
closely allied to the Latrachia than to any of the Repelia proper. But 
I conceive that the affinities of the Labyrinthodonts are clearly with 
the Saurobatrachta (and, in some cranial characters, with the Cec/7e), 
and not with the dura as was at first suggested ; and, with every 
deference to the opinion of so great an authority on all that relates to 
the Labyrinthodonts as von Meyer, I must venture to doubt whether, 
in any characters, these daphrbza exhibit a real approximation to the 
Reptilia. 
At present we are acquainted with two apparently very distinct 
types among the Labyrinthodonts—that of the ARCHEGOSAURIA 
(Archegosaurus), at present known to occur only in the Carboniferous 
rocks, and that of the MASTODONSAURIA (JJastodonsaurus, Labyrin- 
thodon, Capttosaurus, Trematosaurus), which seem to have flourished 
in remarkable abundance during the Triassic epoch. Both groups 
exhibit the sculptured and polished® surface of the crania, the vomerine 
and palatine teeth, the forwardly situated posterior nares, the 
1 Plieninger notes what appears to be a process of a similar character to this in the ribs 
of ALastodonsaurus. 
2 It does not appear that there is any evidence to show that the vertebre ascribed to 
Labyrinthodon by Professor Owen in his paper on the Warwickshire Labyrinthodons (Geol. 
Trans. 1841) are such, while there is much reason to believe they are not. 
3 Whence the term ‘ Ganocephala’ as a distinctive appellation of the drchegosaurta is 
inadmissible. 
