THE RH^TIC ROCKS OF PYLLE HILL, BRISTOL. '227 



I term " Upper Rliaetic," are certainly Rhastic, because in 

 the pale grey limestone " i " we find such characteristic 

 Rhsetic fossils as Cardimn rhwticum, Pecten Valoniensis, 

 Schizodus Ewaldi, Acrodus minimus, Saurichthns acuminatas, 

 and Gyrolepis Alberti. These beds contain also remains of 

 the fresh water endogen Naiadita, also Estheria miniita var. 

 Brodieana, and other smaller ostracoda of fresh- or brackish- 

 water habit, which have been identified by Professor T. 

 Rupert Jones, F.R.S., as belonging to the genus Darwinula, 

 and were very recently described by him as D. liassica 

 (Brodie).* The presence of JEstlieria yninuta var. Brodieana, 

 a form which practically repeats that met with in the Upper 

 Keuper Marls, with or without these other fresh-water ostra- 

 codans and the fresh- water plants, is a characteristic feature 

 of the Upper Rhsetic beds in this country, and would seem 

 to indicate the prevalence of physical conditions during their 

 deposition, of a somewhat different nature to those which 

 prevailed during the deposition of the more purely marine 

 beds of the Lower Rhaetic series.f The presence, however, 

 in these beds of the same marine shells as occur in the 

 Lower Rhgetic beds, such as Giirdium Bhseticum and Pecten 

 Valoniensis, for instance, indicates that the area in which the 

 Upper Rhsetic beds were deposited was not a purely fresh- 

 water one, but Avas either estuarine or liable to occasional 

 incursions of the sea. 



Passing downwards, then, in the section, we enter upon 

 the black Paper Shales or Acicula contorta beds, or " Lower 

 Rhfetic " series, as w^e may call them. As these beds will be 

 pretty well known to all Bristol geologists, and as ample 

 details are given in the accompanying section, I need say 



* " On the Ehsetic and some Liassic Ostracoda of Britain." 

 Quart. Journ. Geol. Soc.^ vol. 1. p. 156. 



t Vide " Monograph of the Fossil Estherise," by T. Rupert Jones, 

 F.G.S., Pal. Soc. (1862), p. 77. 



