72 FORAMINIFERA OF THE CRAG. 



either in a recent or fossil state. We have it from various Liassic marls, and it occurs 

 in many Tertiary deposits in company with other commoner varieties of the same type. 

 In a living condition it is very sparingly distributed. 



Mr. S. Wood found it in the Crag of Sutton, but the specimens were few and small. 



Subgenus — Cristellaria, Lamarck. 



Nautilus, Linn(\ Gmelin, WalTcer and Jacob, Montagu, Maton and Rackett, Pennant, 



Fichtel and Moll, Sowerby, Turton, Fleming, Brown, &c. 

 Lenticulites, Lamarch, Befrance, Nilsson, Hisinger. 

 Lenticulina, Lamarclc, Defrance, Parkinson, &c. 

 PoLYSTOMELLA, Lamarck. 

 NuMMULAKiA (in part), Sowerby. 



Cristellaria, Lamarck, Befrance, UOrbigny, Ehrenberg, Czjzek, Reuse, Miinster 

 and Roemer, Cornuel, Philippi, Hagenow, Bronn, Morris, Parker 

 and Jones, Williamson, Bornemann, Terquem, Carpenter, Costa, 

 Seguenza, Brady, Karrer, &c. 

 NuMMULiNA (in part), B'Orbigny. 



Phonemus, Phaeamum, Antenoe, Robulus, Patrocles, Sphincterulus, Clisi- 

 PHONTEs, Herion, Rhinocuuus, Macrodites, Lampas, Scortimus, Astacolus, 

 Periples, Montfort. 

 Oreas, Montfort, Blainville. 

 LiNTHURis, Montfort, Blainville. 

 Saracen aria, Befrance, B'Orbigny. 

 RoBULlNA, B' Orbigny, Miinster and Roemer, Ehrenberg , Czjzek, Reuss, Bronn, Morris, 



Bornemann, Terqitem, Costa, Karrer, Stache, &c. 

 Hemicristellaria, Hemieobulina, Stache. 



Characters. — Shell round, oval, or oblong, disco-spiral, lenticular, or compressed, bi- 

 laterally symmetrical as regards the longer axis, as is the case with the other Nodosarina ; 

 formed of a spiral set of chambers, in one or more whorls ; chambers either curved or 

 triangular, or both, and variable in size and shape, compactly set, increasing successively 

 in size, slowly or rapidly, and more or less embracing the earlier part of the spire. 

 Aperture excentric, either slit-like, triangular, or round, radiated, usually close to the outer 

 or convex margin, but sometimes pouting and nearer the middle of the septal plane. 

 Surface either smooth or ornamented with any or all of the following features — 

 limbation of the septal lines, ribs, bars, or granules, umbonal knobs, marginal keel and 

 spikes. 



The lenticular Cristellaria without any keel is C. rotulata, Lamarck ; with a keel, 

 C. cuUrata, Montfort ; with a broad keel, commonly toothed, it becomes C. calcar, Linne. 

 When nmch compressed and broadly keeled, it is C. cassis, F. and M. Some lenticular 



