THEIR DISTRIBUTION. 117 



presence of spatangus ovalis,? and ammonites perarmatus, and the ab- 

 sence of products, axini, ammonites Walcottii, nerita costata, astarte 

 minima, and terebratula digona. 



2. Again, the Kelloways rock differs from all the strata above it and 

 below it, by the presence of ammonites calloviensis, and gryphaea 

 dilatata : no stratum in Yorkshire but the Kimmeridge clay contains 

 ostrea delta ; nor is gryphasa incurva found except in lias beds or lias 

 boulders. 



3. It is in the lower part of the coralline oolite that clypeus dimidi- 

 atus, and c. clunicularis abound, but melania striata belongs to the upper 

 layers of that rock. 



These are the principles of investigation which it is proposed to 

 apply to the strata and fossils of the eastern part of Yorkshire, and to 

 illustrate by the aid of the arranged catalogues which follow, and their 

 accompanying plates. 



I shall first present complete lists for each stratum, of all the fossils 

 found in it, distinguishing those which are repeated in other strata, and 

 referring to figures contained in this work ; Mr. Sowerby's Mineral Con- 

 chology ; Mr. Smith's Works ; Mantell's Geology of Sussex ; Young and 

 Bird's Survey of the Yorkshire Coast ; Parkinson's Organic Remains, &c. 



After thus unfolding the evidence which I have collected on the 

 subject, I shall venture to propose some inferences concerning the dis- 

 tribution of organic remains in the rocks of the country which I have 

 undertaken to describe, and likewise endeavour to trace the extent of 

 the agreement in this respect, between the strata of Yorkshire and those 

 of Scotland, the southern counties of England, and several parts of the 

 continent. 



Lastly, I propose to combine the whole into one synoptic list of the 

 organic remains mentioned in this work, arranged in the ascending order 



