GEOLOGY OF THE BRISTOL COAL-FIELD. ^I 



skeletons of Plesiosaurus and Ichthyosaurus coprolites, and thousands 

 of the teeth and scales of fishes. Some of the coprolites when 

 broken open with the hammer exhibit the undigested remains of 

 a meal of some huge Saurian. From this source have been 

 obtained some of the best specimens of the claws and carapaces of 

 Crustacea. So full of fossils is the bone bed that almost every 

 lump will furnish the collector with hundreds of the teeth and 

 scales of such fishes asAcrodus, Sargodon, Gijrolepis, Pholido2}horu8j 

 Saunchthjs, &c. The most interesting of the Aust fossils are the 

 singular teeth of the Ceratodus, of which the Museum has so 

 splendid a collection. The curious shape of these teeth puzzled 

 the naturalists for some time, as there are so many different forms. 

 They average two to four inches in length, and when examined 

 with the lens are covered with most exquisitely sculptured rosettes. 

 For a long time this genus was supposed to be extinct, till a few 

 years since recent examples of the genus were discovered in 

 Queensland, a description of which was given in the Froc. Bristol 

 Nat. Society (vol. I., pt. 2, p. 14 5). 



Upon the black shales lies a very remarkable bed, and full of 

 dendritic markings, from which it gained the name of Landscape 

 Marble, from the resemblance to trees and shrubs. The surface 

 is marked by large mammillations, and has a very conchoidal 

 fracture. The Gotham Marble, as this bed is most frequently 

 called, is very persistent throughout the district, and is conse- 

 quently a good datum for field observation. It thins out, 

 however, at Patchwa)^ station, and is absent in the Aust section 

 and the north-easterly portion of the neighbourhood of Bristol. 

 The best localities for its examination are at Gotham, Bedminster, 

 Saltford, Sec. At these places have been found a great number of 

 Coleoptera, Fishes, and Entomostraca. The following are sections 

 of the localities that have furnished the greatest number of the 

 elytra and wings of insects. 



Section at Lock's Mill. 



Ft. In. 

 Rubble ... ... ... ...10 



Limestone with Osirea ... ... ... 3 4 



