74 



PALAEONTOLOGY 



somewhat resembling Pvrjmra and Golumbella. But since the 

 so-called "cones" of the oolites have proved to be Tornatellce, 



Fig. 18. 



/Secondary Univalves. 



i . Bpinigera, sp. ; Oxford Clay, Chippenham. 



2. Alaria Bentleyi, M. and L. ; Great Oolite, Colly western. 



3. Purpurina Morrisii, Buv., Great Oolite, Minchinhampton. 



4. Nerina?a Bruntrutana, Thurm. ; Corallian, Poland. 



5. Crossostoma Pratti, M. and L. ; Great Oolite, Minchinhampton. 



6. Trochotoma connloides, Desl.; Great Oolite, Minchinhampton. 



7. Neritoma hisinnata, Buv. ; Oxfordian, Ardennes. 



8. Pileolns plicatus, Shy. ; Great Oolite, Ancliff. 



9. Cinulia incrassata, .1. Sby. ; IT. Greensand, Blackdovn. 



10. Acteonina concava, Desl. ; Lias, Normandy. 



1 1. Bellerophina minuta, Sby. ; Gault, Folkestone. 



it may not be unreasonable to distrust these other presumed 

 affinities. The huge univalve of the chalk, which Sowerby 

 called a Dolium, has been described as a Pterocera by d'Orbigny. 

 In the tertiaries siphonated univalves abound, and are mostly 

 referable with certainty to recent genera. The only marked 

 change consists in the comparative abundance of some scarce 

 existing forms, and the absence or rarity of many now most 

 conspicuous. Moreover, the geographical distribution of the 

 genera has undergone a great change since the close of the 

 eocene period. This change is most noticeable in the cold- 

 temperate zone, and is evidently the result of altered climate. 



