NERITINA 



The fossil Neritince occur in the formations above the 

 London Clay, they abound in company with a g:reat pro- 

 fusion of other fresh water shells in the so called " Upper 

 marine formation," and in those Woolwich beds which 

 are decidedly a mixture of marine and fresh water re- 

 mains ; they are also fbund profusely in many similar beds 

 in various parts of France, Germany, &c. 



In our plate, representations are given of 



Fig. 1 & 2. Nerititta Schmideliana; N. perversa, Gmel. and Lam. We liave 

 adopted Chemnitz's specific name, because Gmelins is likely to misleadj iuas- 

 niucli .-.s it is not a reverse shell, though Lamaj'ck says it is. 



3. Neritina Corona,*' Lam. 



4. Inside of the operculum, 



5. Outside of the same, 



6. N. puUigera. 



7. A fossil species from Champagne, which we have named N. callifera; 

 the following are its characters : — Testa obovata, labio interne supra inferiorem 

 anfractus ultimi partem incrassato-expanso. 



Besides these, there v/ill be found a representation of 

 Neritina altavillensis in our plate of Navicella, which was 

 there placed because we at first considered it to be a 

 species of that genus, but upon repeated examination w^e 

 were convinced that it really belongs to Neritina, and, 

 consequently, neither to Navicella nor to Crepidula. 



* The long spines with which this is ornamented are very variable in miniber ; 

 ve have a full-grown specimen wliich has never formed more than one. 



