CHAPTER III 

 UPPER PALAEOZOIC FAUNAS (Pu. xi. AND xn.) 



(A) GENERAL ACCOUNT 



THE products of almost all conditions of sedi- 

 mentation are to be found among British Upper 

 Palaeozoic strata. Some parts of the Old Red 

 Sandstone, and certain sandstones and marls of the 

 Permian, seem to have accumulated on land as moun- 

 tain screes or desert dunes. Other local portions of 

 the Old Red Sandstone give evidence of transitory 

 lacustrine surroundings, while much of the Upper, 

 and parts of the Lower, Carboniferous series were de- 

 posited in fresh water, meandering through delta- 

 swamps. Broad tidal sand-flats of Mid-Carboniferous 

 date produced the Millstone Grit, while shales and coral- 

 reefs indicate different littoral conditions at lower 

 horizons. The Permian Magnesian Limestone was 

 formed in a gulf probably comparable with the Red 

 Sea. Much of the Carboniferous Limestone appears 

 to have developed on the floor of an open, but not 

 deep, sea; the Radiolarian cherts of the Devonshire 

 Culm suggests deposition in abysmal depths. 



Great as is the variety of matrix, the selection of 

 diverse faunal assemblages is somewhat limited. Ter- 

 restrial deposits are, on the whole, sadly unfossiliferous, 

 and even the Coal Measures, with their wealth of plant- 

 remains, enclose but few relics of Invertebrates. The 

 Magnesian Limestone may have lost some proportion 



