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DIVISION XII. CLYPEACEJE. 



GENERA. 



Mostly marine, ad- 

 hering to the rocks and 

 other hard substances 

 bordering the sea. 



V. Animal, p. 73. 



A small hole at the Marine. Y. Animal, 

 summit. PI. 5, fig. 10. p. 72. 



A notch at the poste- Marine. Y. Animal, 

 rior edge. PI. 5, fig. 11. p. 72. 



1. Patella. (1) Lin. 



Oval or almost orbicular, 

 in dilated cones, more or 

 less obtuse and concave 

 beneath. PI. 5, fig. 5,6. 



2. Fissurella. (2) Lam. 



3. Emarginula. (3) Lam. 



4. Scutus. Montf. Par- 

 maphora. Blainv. 



Elongated, flattened ; 

 summit apparent towards 

 the posterior part, which 

 is rounded; the anterior 

 truncated. PI. 5, fig. 4. 



5. SeptariA. Feruss. 

 Navicella. Lam. 



Summit symmetrical, A horizontal plate 

 inclined towards the pos- within, 

 terior edge : an opercu- 

 lum. PI. 5. fig. 23. 

 6 Ancylus. Geoff. 



Conical. 



a. PI. 5, fig. 7. 



b. Plectrophorus, Fer. With an interior winding 



: T»l O. G~ O 



Marine. New Zea- 

 land. Fossil species at 

 Grignon. Animal un- 

 known. 



In the rivers of warm 

 climates. 



Y. Animal, p. 72. 



Y. Animal, p. 63. 



Fresh-water. 

 Terrestrial. 



impression. PI. 6, fig. 2, 3. Teneriffe. Maldives. 



(1) The animal of the fresh- water Patella differs from that of the marine, 

 although the shell has scarcely any distinguishing character. The fossil species 

 P. cornucopia} (pi. 5. fig. 6.) resembles a cap, and is of considerable thickness. 

 Foss. in Alluvia; Crag Marl; Chalk Marl; Clunch Clay ; Alum Shale of Whitby ; 

 Forest Marble. — Grignon; Houdan; Pontoise. 



(2) Foss. in the beds of coarse marine limestone at Grignon^ and in the marl- pits 

 of Touraine. 



{3) Foss. in Limestone analogous to that at Grignon. 



