CORALLINE OOLITE. 133 



into one group or subf or motion. The principal differences between the 

 two rocks arise from the prevalence of remains of the classes zoophyta 

 and radiaria, and the presence of melanias, turbines, and turritellas in the 

 upper beds of the coralline oolite.* Besides a considerable number of spe- 

 cies which are so rare, that we cannot pronounce whether they are pecu- 

 liar to the stratum, or to the quarry that furnished them, as, trigonellites 

 antiquatus, avicula elegantissima and a. tonsipluma, there are several 

 common to this rock, but not yet found in the calcareous grit, as the 

 corallophagous shells, pholas recondita, and modiola ? inclusa ; tellina 

 ampliata ; several crassinse, cucullgeae, ostrea*, and terebratuUe ; and gene- 

 rally the shells of cephalous mollusca. 



Thirdly, a great number of the shells in this stratum occur again, 

 with only slight variations, in several of the conchiferous strata below ; 

 as, turritella muricata and t. cingenda in the inferior oolite ; perna qua- 

 drata in the middle oolite ; mya literata, clypeus clunicularis, and gale- 

 rites depressus in the cornbrash ; corbula curtansata, pecten demissus, 

 spatangus ovalis, ammonites perarmatus, and astacus rostratus in the 

 Kelloways rock. 



Here again we find that agreement between the conclusion obtained 

 by considering rocks in relation to their position and quality on the one 

 hand, and their organic contents on the other, which is the most satis- 

 factory proof of the accuracy of each mode of investigation. For either 

 of these methods of inquiry will convince us of the propriety of group- 

 ing together all the strata, from the coralline oolite downwards to the 

 inferior oolite, in one great family of rocks, naturally divided into two 

 formations, as expressed in the general table of Yorkshire strata, pages 

 32, 33. 



* A striking proof of the accuracy of this generalization is afforded by Mr. Murchison's excel- 

 lent account of the carboniferous and calcareous rocks In Sutherland ; for among the fossils which 

 he enumerates from the calcareous grit of Braambury, none of thete are mentioned. 



