]ll 



PKEFACE. 



The Catalogue of Fossils exhibited in the Museum of Practical 

 Geolog3^ has been out of print for several years. It is intended 

 that some additional cases shall by-and-by be used for the re- 

 ception of fossils, and as these arrangements will for a time delay 

 the preparation of a complete catalogue of the fossils occurring 

 in all the formations, it has been decided to issue it in successive 

 parts, each part containing a list of the fossils of each formation ' 

 belonging to separate groups of strata. One advantage of this 

 plan is that geologists specially interested in any particular group 

 of formations shall be able to procure any one part, such as lists 

 of the fossils of the Silurian, Cretaceous, or Tertiary strata. 



The following catalogue contains lists of fossils beginning with 

 the Neocom'ian or Lower Greensand series of strata, for Ions: known 

 as Lower Cretaceous beds, and these are succeeded in ascendins; 

 order by lists of the fossils of the Gault, Upper Greensand, and 

 the subdivisions of the Chalk. 



Occasionally some geologists have been in doubt as to the precise 

 geological nomenclature that ought to be applied to some of the 

 strata mentioned in this catalogue. One of these, the Blackdown 

 beds, has been referred by different persons to the Upper Green- 

 sand, the Gault, and the Lower Greensand, in whole or in part. 

 At first sight it appears from ordinary physical considerations 

 that they form outlying patches of the Upper Greensand, the 

 whole of this large outlier of Greensands being fi'agn;ents of a 

 much larger extension to the west of the Upper Cretaceous 

 series, for the}' are in places west of the river Axe and Ilminster, 

 capped by patches of Chalk, and it has often been assumed 

 that, as they now stand, they have been simply separated by 

 denudation from the main body of the Upper Cretaceous series 

 which forms the countrj' from Dorsetshire to Beachy Head, the 

 North Foreland, and Flamborough Head. 



When, however, we turn to the fossils of the Blackdown Sands 

 it appears that in about 100 species 40 are found elsewhere in 

 England in undoubted Lower Greensand, 2.9 in the Gault, and 

 about 15 in the Upper Greensand. The predominance of Lower 



41639. Wt. 15929. b 



