Odontopteris cycadea. Zamites distans. Taxodites.
Taumopteris Munsteri. Zamites heterophyllus. Pinites.
Camptopteris crenata. Zamites gracilis.
Pterophyllum dubium.
Nilssonia contigua.
Nilssonia elegantissima.
Nilssonia Sternbergii.
The _Zamites_ seem to be forerunners of the Palms, which make their
appearance in the following epoch; they were trees of elegant
appearance, closely resembling the existing Zamias, which are trees of
tropical America, and especially of the West India Islands; they were so
numerous in species and in individuals that they seem to have formed, of
themselves alone, one half of the forests during the period which
engages our attention. The number of their fossilised species exceeds
that of the living species. The trunk of the Zamites, simple and covered
with scars left by the old leaves, supports a thick crown of leaves more
than six feet in length, disposed in fan-like shape, arising from a
common centre.
The _Pterophyllum_ (Williamsonia), formed great trees, of considerable
elevation, and covered with large pinnated leaves from top to bottom.
Their leaves, thin and membranous, were furnished with leaflets
truncated at the summit and traversed by fine nervures, not convergent,
but abutting on the terminal truncated edge.
The _Nilssonia_, finally, were Cycadeaceæ resembling the Pterophyllum,
but with thick and coriaceous leaves, and short leaflets contiguous to,
and in part attached to the base; they were obtuse or nearly truncated
at the summit, and would present nervures arched or confluent towards
that summit.
The essential characters of the vegetation during the Liassic sub-period
were:--1. The great predominance of the Cycadeaceæ, thus continuing the
development which commenced in the previous period, expanding into
numerous genera belonging both to this family and that of the _Zamites_
and _Nilssonia_; 2. The existence among the Ferns of many genera with
reticulated veins or nervures, and under forms of little variation,
which scarcely show themselves in the more ancient formations.
[Illustration: Fig. 108.--Millepora alcicornis.
(Recent Coral.)]
[Illustration: XVI.--Ideal Landscape of the Liassic Period.]
On the opposite page (PLATE XVI.) is an ideal landscape of the Liassic
period; the trees and shrubs characteristic of the age are the elegant
Pterophyllum, which appears in the extreme left of the picture, and the
Zamites, which are recognisable by their thick and low trunk and
fan-like tuft of foliage. The large horsetail, or Equisetum of this
epoch, mingles with the great Tree-ferns and the Cypress, a Conifer
allied to those of our own age. Among animals, we see the Pterodactyle
specially represented. One of these reptiles is seen in a state of
repose, resting on its hind feet. The other is represented, not flying,
after the manner of a bird, but throwing itself from a rock in order to
seize upon a winged insect, the dragon-fly (_Libellula_), the remains of
which have been discovered, associated with the bones of the
Pterodactyle, in the lithographic limestone of Pappenheim and
Solenhofen.