Rupert Jones, on Bivalved Entomostraca. 51 



of the peaty rivers. These muds and silts, and all their 

 buried shells, and plants, and fish, and crustaceans, sank 

 down, and were covered up and hardened — petrified, often 

 baked by heat, and then, pushed up again by subterranean 

 force, reappearing at the surface as the hard, rocky base of 

 many a new country, and forming the bed of new seas, were 

 eaten into by the ever-working waves, worn down by periodic 

 rains, aided by the scorching sunbeams, the splitting frost, 

 and the incessant agency of the atmospheric gases chemically 

 affecting the surfaces of the rock. 



The sea, now occupying fresh areas, continued its great 

 work of destruction and reparation — wearing down the shores 

 to make up the sea-beds ; and it continued to be the 

 abode of life in its myriad forms ; but they were mostly new 

 forms. In the new deposits laid down on the vipturned edges 

 of the old strata we find Entomostraca again, similar to those 

 of to-day, and in the lagoons and lakes of the Triassic 

 period Estherm abounded. The varying seas, the estuaries, 

 bays, gulfs, and oceans of the Oolitic period, when land 

 was rising here and sinking there — the sea ever rolling under 

 its tidal laws, and coming and going amongst the ever- 

 shifting land — these seas, we know, swarmed with Entomos- 

 traca, amongst the world of marine creatures, and the rivers 

 and lakes were swarming too. The land that bore the great 

 Iguanodon and Megalosaurus — gigantic lizards wandering 

 over the marshy grounds, just as the amphibious Hippopotami 

 of to-day wallow along the African swamps —had its great 

 rivers ; and their deltas, like those of the Ganges and Missis- 

 sippi, consisted of mudbanks and muddy lagoons, full of 

 Uniones, Paludbue, Cyrence, and other shell-fish, and above all 

 with Cypridce and Estherice, feeding on the dead molluscs and 

 fish. 



The Sussex marble is mainly composed of these sometimes ; 

 some beds of freestone at Swanage are wholly made up of 

 them, and flake after flake of black clay, once mud, may 

 easily be picked by the hand, in the Isle of Wight, in clift's 

 some miles extent, from beds of shale nearly two hundred 

 feet thick, every surface being thickly coated with the shells 

 or carapaces of these minute creatures. What durable wit- 

 nesses of a long-past age ! 



The '^ Age of Reptiles " passed away, the land and its 

 rivers went down, the sea-bed and the estuaries were coated 

 over with new sands and clays, derived from ncAV cliffs and 

 new lands, washed by the untiring, enduring sea. Some 

 parts of what is now the European area sank several hundred 

 feet, and was covered by a deep sea, and in this were formed 



VOL. XVI. e 



