230 HISTORICAL PALAONTOLOGY. 
fore, with those of the preceding Triassic formation. The 
ferns are very abundant, and belong partly to old and partly 
to new genera. ‘The Cycads are also very abundant, and, on 
the whole, constitute the most marked feature of the Jurassic 
vegetation, many genera of this group being known (Peero- 
phyllum, Otozamites, Zamites, Crossozamia, Williamsonia, Buck- 
landia, &c.) The so-called ‘‘ dirt-bed” of the Purbeck series 
consists of an ancient soil, in which stand erect the trunks of 
Conifers and the silicified stools of Cycads of the genus JZantel- 
fia (fig. 160). The Conifere of the Jurassic are represented by 
Fig. 160.—Mantellia (Cycadeoidea) megalophylla, a Cycad from the Purbeck 
**dirt-bed.” Upper Oolites, England. 
various forms more or less nearly allied to the existing 4vaw- 
carie; and these are known not only by their stems or 
branches, but also in some cases by their cones. We meet, 
also, with the remains of undoubted Endogenous plants, the 
most important of which are the fruits of forms allied to the 
existing Screw-pines (Pandanee), such as Podocarya and Kaida- 
carpum. So far, however, no remains of Palms have been 
found ; nor are we acquainted with any Jurassic plants which 
could be certainly referred to the great ‘“ Angiospermous ” 
group of the Exogens, including the majority of our ordinary 
plants and trees. 
Amongst animals, the /vofezoans are well represented in 
the Jurassic deposits by numerous /oraminifers and Sponges ; 
as are the Calenterates by numerous ‘Corals. Remains 
of these last-mentioned organisms are extremely abundant 
in some of the limestones of the formation, such as the 
“Coral-rag”’ and the Great Oolite ; and the former of these 
may fairly be considered as an ancient “reef.” The Augose 
Corals have not hitherto been detected in the Jurassic rocks ; 
and the ‘* Zabulate Corals,” so-called, are represented only by 
examples of the modern genus AZi//efora. With this excep- 
