23 
the triassic mastodonsaurus had the same parts completely 
ossified. The only other cases cited in the same address as 
affording apparent confirmation to the doctrine of progres- 
sive development are the dentition of anoplotherium as con- 
trasted with that of recent artiodactyles, and the advance in 
degree of ossification of some cartilaginous fishes and some 
crocodilia and lacertilia. It is worth notice that the case of 
the labyrinthodonts upon which the chief stress is laid, has 
since the delivery of this address broken down altogether. 
We can now show from the specimen just described that 
the vertebral column of the carboniferous labyrinthodont 
is as well ossified as that of any of its triassic allies. Pholido- 
gaster also exhibits osseous vertebral centra, so that we can 
fairly say (if Mr. Huxley's summary of the evidence be 
reliable) that of three-fourths of the examples cited, one-half 
are already shown to be fallacious. It would be wandering 
too far to pursue this subject any more. The present con- 
dition of geological discovery, while not disproving the theory 
of descent with modification, which is on other grounds so 
probable, seems to discourage all attempts to refer the present 
life of the earth to a single germ developed in the remote 
past. If we must use metaphors, perhaps the most appropriate 
would be — divergence in all directions from an undifferen- 
tiated axis, the length of the axis indicating the geological 
relation. Should this view be advanced with those proofs 
which the present position of palaeontology affords, I hope it 
may be discussed with that impartial and searching scepticism 
which is so necessary for the attainment of scientific truth. 
Note. — Sept., 1869. A description of this fossil, accompanied by 
drawings of some of the details, will be found in No. 99 of the Geo- 
logical Journal . Professor Huxley thinks it best to recognise the 
fossil as a new generic and specific form, for which he proposes the 
name of Pholiderpeton scutigerum. 
