54 



GEOLOGY OF THE BRISTOL COAL-FIELD. 



at different states of the tide became covered by the tide. Here 

 gigantic saurians congregated to enjoy a plentiful supply of their 

 favorite food, while in the mud lay buried the Ceratodus, just as 

 the Lepidosiren is now found in the present swamps of Western 

 Africa. 



The saurian coprolite being chiefly made up of the bones 

 of smaller Saurian and fishes^ contain from twenty-five to fifty 

 per cent, of phosphate^of lime. 



The following is a list of the principal fossils of the Rhaetic beds 

 in the immediate neighbourhood of Bristol. Most of them may be 

 collected at Aust, Bedminster, Ashley Down, Sakford, and 

 Willsbridge. — 



