244 On the Evolution of the Vertebrata. [ March, 
A ganged arch; palatine arch imperfect; nasals, premaxillaries and caudal verte- 
tinct 
Cenk wilh «aaah Kae Urodela,’ 
No beraa or palatine arches; nasals and premaxillary, also caudal vertebræ, dis- 
tinct, Ae a a a Seowdecwescceetees Trachystomata. 
III. Supraoccipital, intercalare and supratemporal bones wanting. Frontals 
and parietals connate ; aan bones and caudal vertebre confluent. 
Premaxillaries distinct from nasals; no palatine arch; astragalus and calcaneum 
elongate, forming a distinct D of the lim 
The probable phylogeny of these orders as imperfectly indi- 
cated by palæontology is as follows: 
Anura ae 
Urodela Trachystomata 
Proteida 
Stegocephali 
Embolomeri Rhachitomi? 
Ganocephala® 
An examination of the above tables shows that there has been 
in the history of the Batrachian class a reduction in the number 
of the elements composing the skull, both by loss and by fusion 
with each other. It also shows that the vertebrae have passed 
from a notochordal state with segmented centra, to biconcave 
centra, and finally to ball and socket centra, with a ‘great reduc- 
tion of the caudal series. It is also the fact that the earlier forms 
(those of the Permian epoch) show the most mammalian charac- 
ters of the tarsus and of the pelvis The later forms, the sala- 
manders, show a more generalized form of carpus and tarsus and 
of pelvis also. In the latest forms, the Anura, the carpus and- 
tarsus are reduced through loss of parts, except that the astraga- 
_ lus and calcaneum are phenomenally elongate. We have then, 
in the Batrachian series, a somewhat mixed kind of change ; but 
it principally consists of concentration and consolidation of parts. 
The question as to whether this process is one of progression Or 
1 Probably includes the Gymnophiona, 
of Eryops is much like that of the Theromorph reptiles. See 
heirs Amer. — Soc., 1884, p. 38, 
