THE CRETACEOUS PERIOD. 



The Univalves (Gasttropods) of the Cretaceous period are 

 not very numerous, nor particularly remarkable. Along with 

 species of the persistent genus Plcurotomaria and the Meso- 



Fig. ^.Hippurites Toucastann. 

 A large individual, with two smaller 

 ones attached to it. Upper Cretace- 

 ous, South of Kurope. 



Fig. 200. Valuta elongaia. 

 White Chalk. 



zoic Nerin&a, we meet with examples of such modern types 

 as Turritella and Natica, the Staircase-shells {Solarium}, the 

 Wentle-traps (Scalaria], the Carrier-shells (Phorus), &c. To- 

 wards the close of the Cretaceous period, and especially in 

 such transitional strata as the Maestricht beds, the Faxoe 

 Limestone, and the Pisolitic Limestone of France, we meet 

 with a number of carnivorous (" siphonostomatous ") Uni- 

 valves, in which the mouth of the shell is notched or pro- 

 duced into a canal. Amongst these it is interesting to 

 recognise examples of such existing genera as the Volutes 

 (Valuta, fig. 200), the Cowries (Cyprcea), the Mitre-shells 

 (Mitra), the Wing - shells (Strombus), the Scorpion - shells 

 (Pleroceras], &c. 



