UPPER PALAEOZOIC FAUNAS 157 



Eastern England, but the Magnesian Limestone therein 

 deposited gives but feeble indication of the important 

 marine deposits of the European and Asiatic Permian. 

 Before the end of the period, the gulf was silted up, and 

 almost the whole of the British area was brought under 

 the desolate monotony of the Triassic desert. 



Although many of the groups of organisms dominant 

 in Lower Palaeozoic times persisted through these later 

 periods, there is a marked difference in the general faunas 

 of the two eras. Graptolites have become extinct (for 

 all practical purposes) ; Brachiopods, though still abun- 

 dant, are represented by acmaic stages of quite different 

 groups from those successful in the preceding era ; while 

 Trilobites have lost much of their earlier prominence. 

 If four types are to be selected as particularly important 

 in Upper Palaeozoic times, the choice would un- 

 doubtedly fall on Tetracorals, Camerate Crinoids, 

 Productid and Spiriferid Brachiopods, and " Goniatite " 

 Cephalopods. Many groups of Arthropods are more 

 fully known from the Carboniferous than from any other 

 horizons ; but the special nature of their occurrence in 

 the Coal Measures makes comparison with previous or 

 later faunas impracticable. 



(B) PROTOZOA 



The Protozoa are more fully represented in the 

 Upper Palaeozoic than in older periods. Foraminifera 

 and Radiolaria both play the part of rock-formers in 

 the Carboniferous series ; the " Radiolarian Culm " of 

 Devonshire is one of the richest stores of these small 

 fossils at any horizon in British strata. In the North of 

 England, important masses of the Carboniferous Lime- 

 stone are built of Foraminifera. It is a point of interest 

 that in both cases the respective orders include many 



