62 Guide to the Invertehrata. 



Bryozoa. which the upper was once regarded as a coral growing as a parasite 



GALLERY on a Fenestella. 

 VIII. 



The Permian species are few in number, and the five chief 



cases species are illustrated by a representative series. Three specimens 



86a & 86b, too large for the table-case are placed in Wall-case 12a. 

 12a. The next fauna represented in England is that of the Jurassic 



system, which shows a great advance from that of the Palaeozoic ; 

 old types such as Fenestella^ Penniretepora, Acanthocladia disappear, 

 and species belonging to existing genera form the largest part of 

 the fauna. Among these, Stomatopora, Berenicea, and Diastopora 

 are the most important, and are illustrated by an extensive series 

 of specimens. These are associated with forms such as Ceriopora^ 

 which are survivals of the Palaeozoic group of Trepostomata, and 

 others such as Theonoa and Apsendesia, which are typically 

 Mesozoic. 



The ensuing Cretaceous fauna in many ways resembles the 

 Jurassic. Trepostomata survive, and the Cyclostomata are still in 

 the ascendancy. Examination, however, of the specimens ex- 

 hibited, shows that the Cheilostomata are now fairly abundant, 

 as we may see by the numerous species of Memhranipora and 

 Onychocella, and the presence of more specialized genera such 

 as Crihrilina. 



Passing to the Eocene, we find that the fauna in England 

 becomes much smaller, though that of the Mediterranean Basin 

 at the same period was very large. The forms, moreover, are 

 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. Hence genera such 

 as Idmonea are represented only by small delicate colonies (see 

 e.g. Idmonea coronopus, from the Paris Basin), which are in striking 

 contrast to the massive growths found in Italy and Austria. 

 The fauna is therefore aberrant, and includes a remarkably 

 high percentage of peculiar species. Among these, Orhitulipora 

 petiolus, consisting of a disc supported on a short stem (see 

 e.g. specimen, B. 4349), Adeonellopsis JVetherellt, and JVotamta 

 Wetherelli, are the most interesting species; Schi%oporella 

 magnoaperta, Smithia tulularis, and EntalopJiora tergemina, are 

 of interest as representing modern types of existing genera. 



The Pliocene in England is much richer than the Eocene, and 

 comparison need only be made between the small fragile specimens 



