BUODIE — GEOLOGY OF GLOUCESTERSHIRE. 



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tnincatum, whole blocks being nearly entirely composed of them ; and 

 several beds of oysters were also obtained in situ at different depths. 

 It is to be observed further, that the bivalves preponderate over the 

 gasteropodous univalves in the Lias generally, and in this particular 

 zone are several species which are limited to it. The Cephalopoda 

 (Ammonites, Belemnites, and Nautilus) are not in this division repre- 

 sented by so many species as in others ; although individuals are 

 numerous, and indicate a considerable depth of water. Ilemains of 

 Saurians are scarce, only a few bones and detached vcrtebrcc of Piesi- 

 osauri having been met with ; presenting thus a wide contrast with the 

 abundance of those marine monsters in the lower part of this for- 

 mation. 



In our next article, when describing the underlying beds, which, in 

 fact, compose the main mass of the Lias in Gloucestershire, we hope to 

 dwell somewhat longer on the habits and structure of the remarkable 

 marine reptiles which played so x;)rominent a part in the zoological 

 history of the earlier stages of the deposit. Indeed, there is only one 

 other geological period during which such creatures swarmed in equal 

 profusion, and in such numbers that they must have, been the tyrants 

 of the deep, so that the eras of the Lias and Wealden have been not in- 

 aptly termed the ''age of reptiles." And, although these remains 

 are few and far between in the upper and middle part of the series in this 

 county, in other places they are much more frequent, as in the upper 

 Lias at Ilminster, in Somersetshire, and at Whitby, in Yorkshire. 

 Most people are probably aware of the general form and appearance of 

 these saurians : a fine collection of them may be seen at the British 

 Museum, and in various local collections, both public and private, so that 

 ample facilities are not wanting for making acquaintance with these 

 extinct animals,'^' even to those who have little or no knowledge of 

 Geology. 



TliQ gardens of the Crystal Palace are enriclied ^yith noble models of tLe^e 

 creatures. — Ed. Geologist. 



