21 
includiug anthracosaui'us and the triassic labyrinthodonts, 
and specially distinguished by their well ossified vertebral 
column, and the presence of two occipital condyles ; and 
archegosauria (archegosaurus, pholidogaster, &c.) in which 
the vertebral column is notochordal, and the occipital condyles 
either cartilaginous or wanting altogether. This classification 
will be understood at a glance by the aid of the appended 
table : 
Amphibia (Batrachia of Cuvier). 
Batrachia. 
Saurohatrachia. 
Ophioinorjjha. 
L ahyrin thodontia. 
Archegosauria (Ganocephala, Ow.) 
Mastodonsauria (Labyi'inthodontia, Ow.) 
This imperfect account must suffice for the present. I hope, 
with Professor Huxley's assistance, to bring fresh details to 
light. All such fuller information, with any necessary cor- 
rections of the present hasty sketch, will be found in the 
forthcoming volume of the Geological Society. Let me urge 
any members of this society who have in their possession 
vertebrate remains from the Yorkshire coalfield to study 
them afresh, and search particularly for those batrachian 
characters which are so easy to detect in ahnost any fragment. 
The relations of the carboniferous and triassic labyrintho- 
dontia have been discussed with reference to the doctrine of 
progressive modification, and as the specimen just described 
throws additional light upon this important inquiry, a few 
words on the subject will, I trust, be pardoned. Lamarck's 
views on the transmutation of species, though so crude and 
unsupported by adequate evidence, have long exercised an 
important influence on geological speculation. It has been 
asserted over and over again that the fossil remains of suc- 
cessive strata exhibit an uniform advance in degree of organi- 
