Vol. OO.] SECTIONS IN THE 1JR1STOL DISTRICT. 193 



The Bev. J. F. Blake asked whether the Author could give any 

 more information about the grev beds which yielded Microlestes. 

 This at least seemed to indicate terrestrial conditions, but the 

 J3one-Bed was the commencement of the Liassic deposits. This 

 kind of bed was often the introduction to a new group of strata — 

 the Bhaetic forming the base of the Lower Jurassic, as the Cornbrash 

 formed the base of the Upper Jurassic. The)' always contained some 

 fossils of the older rocks mixed with those of the newer types, 

 ;md thus were aggregates; but they could not be called 'passage- 

 beds ', as the change was rapid and both sets of fossils were intro- 

 duced together. 



The Author replied that, although there were several horizons at 

 which teeth and bones were abundant, there was one well-marked 

 horizon near the base of the Black Shales, containing pebbles. This 

 he called the Bone-Bed. Although a Bhaetic mammal, Microlestes 

 appeared in the infra-Bone-Bed Series in England, because it could 

 wander over the land when the Rhaetic Ei a had commenced, a little 

 earlier, in Germany. 



Q. J. U. S. No. 238. 



