348 FORAMINIFERA OF THE CRAG. 



Occurrence. — JV. depressula, found in the Arctic seas, and abounding in the 

 North Atlantic, occurs also in the South Atlantic, South Pacific, Red Sea, 

 and elsewhere, usually at less than 100 fathoms. " It is the only member of the 

 genus that is common in estuaries and brackish water pools" (H. B. Brady). 



Under one name or another this form and its varieties have been described 

 from the Eocene of Paris, the Miocene of Vienna and Calabria, the Pliocene of 

 Rhodes, and the Post-Tertiaries of Norway and the British Islands (H. B. 

 Brady). 



The specimen here figured was collected from the Coralline Crag of Sutton by 

 S. V. Wood some years ago. 



Genus 2. — Poltstomella, Lamarck, 1822. 



Cornu ammonis, Plancus. 



Nautilus, Linne, Favanne, Walker and Jacob, Soldani, Gmelin, Schreibers, Fichtel 

 and Moll, Montagu, Adams, Ifaton and Packett, Pennant, Parkinson, 

 Turton, Brown, Fleming. 



Polystomella, Lamarck, Defrance, Blainville, d'Orbigny, Pisso, Sander Pang, 

 Menke, Deshayes, Potiez and Michaud, Michelotti, Fgger, 

 Sowerby, Brown, Macgillivray , Thorpe, Williamson, Parker and 

 Jones, Carpenter, Wood, Seguema, Karrer, Dawson, Brady, von 

 Gilmbel, Alcock, Parfitt, Bunzel, von Reuss, Czjzek, Putimeyer 

 Bronn, d'Eichwald, Schultze, Schivager, Hoernes, Abich, Terrigi, 

 Targioni, A. Silvestri, Costa, Terquem, Peeve, Goes, Stein- 

 mann, Crouch, Harvey, Mantell, Gosse, Harting, Greene, 

 Toula, von Zittel, Nicholson, Mobius, Hamilton, West, Hogg, 

 Verworn, Lister, Walther, Prestwich, llackie, Uhlig, Olszewski, 

 Quenstedt, Biitschli, Schlumberger, Fornasini, Millett, Cooke, 

 Neumayr, and others. 



Elphidittm, Geophonus, Pelorus, Chrysoltts, Andromedes, Sporiltjs, The- 

 meon, and Cellanthtjs, de Montfort. 



Eobulina, von Munster, d'Orbigny. 



Cristellabia, Lamarck. 



Vorticialis, Lamarck, Defrance, Blainville. 



G-eoponus, Ehrenberg. 



Polystomatium, Ehrenberg. 



Noniontna, Boll, Egger. 



Helicoza, Mobius. 



General Characters. — Shell free, equilateral, nautiloid; convolutions numerous, 

 the outermost embracing more or less completely all the preceding whorls ; 

 segments numerous in each convolution ; their posterior margins marked by 

 crenulations (less definite in those of simpler growth), formed by tubular retral 



