nes, each carpel bearing two ovules on its margin. In Cycas,
however, no female cone is produced, but the leaf-like carpels, bearing
from two to six ovules each, are borne directly on the main stem of the
plant in rosettes alternating with those of the ordinary leaves--the
most primitive arrangement known in any living seed-plant. The
whole Order is relatively primitive, as shown most strikingly in its
cryptogamic mode of fertilisation, by means of spermatozoids, which it
shares with the maidenhair tree alone, among recent seed-plants.

In all the older Mesozoic rocks, from the Trias to the Lower Cretaceous,
plants of the Cycad class (Cycadophyta, to use Nathorst's comprehensive
name) are extraordinarily abundant in all parts of the world; in
fact they were almost as prominent in the flora of those ages as the
Dicotyledons are in that of our own day. In habit and to a great extent
in anatomy, the Mesozoic Cycadophyta for the most part much resemble the
recent Cycadaceae. But, strange to say, it is only in the rarest
cases that the fructification has proved to be of the simple type
characteristic of the recent family; the vast majority of the abundant
fertile specimens yielded by the Mesozoic rocks possess a type of
reproductive apparatus far more elaborate than anything known in
Cycadaceae or other Gymnosperms. The predominant Mesozoic family,
characterised by this advanced reproductive organisation, is known
as the Bennettiteae; in habit these plants resembled the more stunted
Cycads of the recent flora, but differed from them in the presence of
numerous lateral fructifications, like large buds, borne on the stem
among the crowded bases of the leaves. The organisation of these
fructifications was first worked out on European specimens by
Carruthers, Solms-Laubach, Lignier and others, but these observers had
only more or less ripe fruits to deal with; the complete structure of
the flower has only been elucidated within the last few years by the
researches of Wieland on the magnificent American material, derived from
the Upper Jurassic and Lower Cretaceous beds of Maryland, Dakota and
Wyoming. (G.R. Wieland, "American Fossil Cycads", Carnegie Institution,
Washington, 1906.) The word "flower" is used deliberately, for reasons
which will be apparent from the following brief description, based on
Wieland's observations.

The fructification is attached to the stem by a thick stalk, which,
in its upper part, bears a large nu