116 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 17, 



Of Saurians, we meet with teeth of the Ichthyosaurus, Plesiosau- 

 rus, and Megalosaurus, but parts of the skeleton are rare. 



The Stonesfield Slate is remarkable for its peculiar mechanical con- 

 dition, being readily fissile into thin stone-tiles after exposure, and 

 possessing a comparatively low specific gravity, so that from appear- 

 ance and lightness it makes a capital roofing-material ; it is much 

 quarried at Birdlip, Miserdine, Sevenhampton near Cheltenham, 

 and in the Stow district ; at the two latter places more especially 

 it offers an abundant list of fossil remains, of a curious character, 

 such as 



Plants, both aquatic and terrestrial. 

 Insects, of several families. 



Saurians, including the Megalosaurus and the Pterodactylus. 

 Fishes, especially fine palatal teeth of Psammodus. 

 Cirrhipedes. — Pollicipes ooliticus, Buckman. 

 Echinoderms. — Astropecten Cotteswoldice, Buckman, and Astro- 

 pecten Bakeri, Buckm. : a single specimen of the latter is in my 

 cabinet from the lower beds at Minchinhampton ; and with these a 

 large series of shells, amongst which are Ammonites gracilis, Buckm., 

 Belemnites fusiformis, Park., and B. Bessinus, D'Orb. 



In proof of the fossil riches of Great Oolite of Minchinhampton 

 alone, the following enumeration of my friend Mr. J. Lycett may 

 not be out of place. 



Species. 



Conchifera 109 



Monomyaria 44 



Brachiopoda 8 



Gasteropoda 142 



Cephalopoda 9 



Radiata 9 



Total determined by Mr. Lycett. . . 321 species. 



6. Bradford Clay. 



Our Bradford Clay may be described as a yellowish marl, as it 

 always contains a large per-centage of lime ; sometimes indeed it is a 

 loose calcareous sand : it rests at the top or in hollows of the Great 

 Oolite limestones. 



In Gloucestershire this bed seldom attains to the thickness of 

 10 feet, and indeed is mostly altogether absent; but, when so, its 

 position is indicated by an irregularity in the deposition of the upper 

 beds of the Great Oolite, which marks the commencement of the new 

 conditions that brought in the thick clays and siliceous limestones of 

 the Forest Marble deposit. This irregularity, always more or less 

 observable, may be regarded as the point of oscillation, indicating a 

 change of circumstance ; and thus it may well serve as a natural 

 boundary-line of the Great Oolite and Forest Marble. 



The position of the Bradford Clay will be readily made out by 

 attention to the Section, PI. VII. ; and the graduation from the Great 

 Oolite to the Forest Marble beds is well seen at the Hare Bushes 

 Quarry, a mile east of Cirencester. 



