55) 
spirally arranged, rather reduced fronds, either entire or pinnately 
divided. In each fork was a subsessile fructification surrounded 
by bracts. These fructifications are met with in two forms, prob- 
ably representing different ages and states of preservation. In the 
one it consists of a small pyriform axis separated from the flower- 
stalk by a swollen striated collar bearing oval pollen-sacs on the sur- 
face of greatly reduced scale-like appendages. Ovulate structures 
on the pyriform axis appear to have been vestigial. In the second 
type the axis is hidden by the linear bracts, but its surface reveals 
a regular pattern of interseminal scales, between which the micro- 
pylar ends of the seeds are seen, indicating an organization of the 
ovule like that of the cyeadeoids and Williamsoita. 
Wilhamsonia was a larger and more varied type, especially 
abundant and world wide in its distribution in middle Mesozoic 
times. The stems are elongated and slender, but reach diameters 
of several inches and bear large pinnate fronds at the forks and 
terminally. The so-called flowers, to which the term [Viliamsonia 
was originally applied, and which are usually found detached, con- 
sist of a central ovulate receptable surrounded by a lobed disk 
bearing the pollen-sacs. These disks vary greatly in details, and 
various generic names are used to distinguish the different kinds. 
The Cycadeoids, of which the one shown is typical, have for the 
most part simple squat tuberous trunks with a crown of one or 
several whorls of long graceful pinnate fronds, and are armored 
with the persistent leaf bases. Many are found in a beautifully 
petrihed condition in the late Jurassic and lower Cretaceous, s¢ 
that their structural features are exceedingly well known. 
Instead of terminal cones there are short bract-covered axillary 
branches among the old leaf bases, which expand just at the sur- 
face of the armor clad trunk into hemispherical or conical recepta- 
cles. At the base of this receptacle is a sort of a collar which 
carries a whorl of bipinnate organs often called stamens, since 
they produce the pollen. After this is shed they wither, and con- 
O 
sequently are not often petrified. 
The receptacle carries quantities of stalked ovules, tightly packed 
iat only their tips, which give access to 
ry 
These ovules develop into small seeds, 
between sterile scales so t 
the sperms, are visible. 
each of which is almost completely filled by a large embryo having 
