GEOLOGY OF THE BRISTOL COALMELD. ' 281 



The insect remains in the bed No. 3 are the Elytra of Coleoptera, 

 and the wings of Hemiptera and Orthoptera. Above these beds in 

 one of hardened clay is a layer of Monotis decussata that cannot be 

 distinguished from those of Garden Cliff, near Westbury-on- 

 Severn. With these pretty little bivalves are scales of different 

 species of Pholidophorus, and teeth of Hybodas, Acrodus, and 

 Saurichthys, but, so far as I am aware, none of the Ceratodus teeth 

 have been met with nearer than Aust. 



Everywhere in these strata occur several beds of limestone 

 abounding with Cardium Rhoeticum, Avicula costata, and Pecten 

 Valoniensis. The following section of Aust Cliff, perhaps, shews 

 the sequence of the several Rhcetic strata very plainly : — 



Ft. In. 

 Grey Argillaceous Limestone of the Lima series 2 6 

 Limestone of Planorbis series, with Elytra of 



Coleoptera, Fish Scales, ^'c. ... ... 25 2 



Avicula beds ... ... ... ... JO 6 



Celebrated Bone bed ... ... ... 8 



Keupcr Marls^ with Selenite and Cuelestine ... 123 o 



The above bone bed is the one so well known for affording the 

 curious teeth of Ceratodus, bones and coprolites of Saurians. The 

 list of fossils is exceedingly numerous, and has been detailed in a 

 former paper. These beds again occur at Bishopsworth at the 

 same height, and are there well m.arked by a small rivulet that has 

 worn a passage through the stiff clays of the Avicula beds. It is 

 here that the Cotham marble before-mentioned occurs, and is 

 everywhere useful as being a boundary line between the Rhoetic 



