BRYOZOA OR POLYZOA. 
121 
Tlie Permian species are few ; but three larger masses 
of Fencstclla and Stjnoclctdia, another Cryptostonie, are 
mounted on blocks. 
Tlie next fauna represented in England is that of the 
Jurassic system. This shows a great advance on that of 
tlie Palaeozoic ; old types such as Fencstclla, Fennirclcpoi'a, 
Acanthocladia disappear, and species belonging to existing 
genera form the larger part of the fauna. Among these the 
Cyclostomes, Stamatopora, Berenicea, and Diastopora are 
important, and are illustrated by an extensive series of 
specimens, but Thconoa mwA Apscndcsia are typically Jura.ssic. 
These are assochated with forms such as Ceriopora, which 
are survivals of the Trepostomata. 
The ensuing Cretaceous fauna in many ways resembles 
the Jurassic. Trepostomata survive, and the Cyclostomata 
are still in the ascendant. Examination, however, of the 
specimens exhibited shows that the Cheilostomata are now 
fairly abundant, as w^e may see by the numerous .species of 
Membranipora and Onycliocclla (Fig. 65) and the presence of 
more specialised genera such as Oribrilina. 
Passing to the Eocene we find that the fauna in England 
became smaller, though that of the Mediterranean Basin at 
the same period was very large. The forms, moreover, were 
scarce and dwarfed, as they lived in a sea exposed to the 
north and cut off from the warm waters of the Mediterranean 
by a land barrier across Central France and Germany, 
dlence in our series genera such as Idmonca are represented 
only by small delicate colonies (see also Idmonca coronopus, 
from the Paris Basin), which are in striking contrast to the 
massive growths exhibited from Italy. In addition to these 
general differences, the fauna includes a high percentage of 
peculiar species, among which Orbituli 2 wra pctiolus, consisting 
of a disc supported on a short stem (see specimen B. 4.349), 
Adconcllopsis Wetherelli, and Notamia Wcthcrclli. are the 
most remarkable. The species of the still existing genera 
Schizoporclla, Bmittia, and Fnlaloj^hora, on the other hand, 
are quite modern in form. Flxcept for the Cyclostomes 
Idmonca and Fntalo 2 )hora, all the genera mentioned in this 
paragraph are Cheilostomes. 
The Pliocene in England is much richer than the 
Eocene, and comparison need only be made between the 
small fragile specimens from the latter and such massive 
colonies as those from the Crags, to realise that the Bryozoa 
W'ere then living under more favourable conditions; the 
Gallery 
VIII. 
Case A6, 
West Side 
Case A6, 
West and 
East Sides. 
Case A6, 
East Side. 
Case A5, 
East Side. 
Wall-case 
12a. 
