CHAPTER 1.12.

1859-1860.

[The programme laid down in 1857 was steadily carried out through a
great part of 1859. Huxley published nine monographs, chiefly on fossil
Reptilia, in the proceedings of the Geological Society and of the
Geological Survey, one on the armour of crocodiles at the Linnean, and
"Observations on the Development of some Parts of the Skeleton of
Fishes," in the "Journal of Microscopical Science."

Among the former was a paper on Stagonolepis, a creature from the Elgin
beds, which had previously been ranked among the fishes. From some new
remains, which he worked out of the stone with his own hands, Huxley
made out that this was a reptile closely allied to the Crocodiles; and
from this and the affinities of another fossil, Hyperodapedon, from
neighbouring beds, determined the geological age to which the Elgin beds
belonged. A good deal turned upon the nature of the scales from the back
and belly of this animal, and a careful comparison with the scales of
modern crocodiles--a subject till then little investigated--led to the
paper at the Linnean already mentioned.

The paper on fish development was mainly based upon dissections of the
young of the stickleback. Fishes had been divided into two classes
according as their tails are developed evenly on either side of the line
of the spine, which was supposed to continue straight through the centre
of the tail, or lopsided, with one tail fin larger than the other. This
investigation showed that the apparently even development was only an
extreme case of lopsidedness, the continuation of the "chorda," which