JONES AND PAKKER, FOKAJIINIFERA OF LONDON CLAY. 87 



Sow., JV. affinis, D'Orb., etc. Common in the London Clay, the 

 Vienna basin, the subapennine Tertiaries, the Malaga, San Domingo, 

 and other clays, and recent at Jamaica. 



Fig. 10. Nodosaria Raphanus, Linn. This is less developed com- 

 pared with the foregoing, and is equally, if not more abundant in the 

 recent and fossil state. Its modifications are endless, and its names 

 proportionally numerous. There is no real demarcation either between 

 N. Raphanus aud N. Raphanistrum, or between them and their sub- 

 varieties, however modified as to size and number of riblets, close- 

 ness or division of the chambers, conicity or cylindricity of the shell, 

 its straightness or curvature, or the more or less central position of 

 the aperture. Gradual changes lead us, on one hand, to the costu- 

 late and prickled Dentalinse and Marginulinse above referred to ; and, 

 on the other, to the smooth Nodosaria radicula and Dentalina com- 

 munis ; whilst Vaginulinae, MarginulinaD, and Cristellariae, with and 

 without riblets, come out, as it were, from the straighter forms with- 

 out any real specific differences, however convenient it may be to 

 retain distinct names for nearly all the modifications alluded to. 



Tig. 12. Marginulina JVethereUii, Jones, in Morris's Catal. Brit. 

 Foss. 1854, p. 37. Montagu had this little shell also in the Boysian 

 Collection, doubtlessly from the cliff-washings of Kent, and referred it, 

 erroneously, to what is now known as a narrow variety of Peneroplis 

 planatus. It is one of the most common of the Foraminifera of the 

 London Clay, and though somewhat similar Marginulinse occur in 

 other Tertiary beds (San Domingo), and even in the Chalk (of Meck- 

 lenburg),* and the Clays of the Oolites, yet it remains as a distinct 

 variety. It had a peculiar habit of ending its growth with one or 

 more simple, contracted, smooth, dentaline chambers, figured both by 

 Montagu and Sowerby. 



Fig. 13. Cristellaria cultrata, Montfort. A common, nautiloid, 

 keeled Cristellaria, common in many deposits, both of Secondary and 

 Tertiary age, and abundant in the living state in the existing seas at 

 many places. When the keel is wanting, we have G. rotulata, La- 

 marck ; when the shell is large-keeled and rowelled, it is G. Galcar, 

 Linn. ; when flattened and broad, it is G. Gassis, Fichtel and Moll. 



Figs. 14-18. These little liotaline shells are small varieties of 

 Rlanorbulina farcta, Fichtel and Moll (Ann. Nat. Hist. 3 ser. vol. v. 

 p. 177, etc.). They range between the varieties figured and described 

 by D'Orbigny as Rotalia Haidingeri and R. JJngeriana ; and Eeuss's 

 R. ammonoides, D'Orbigny's R. Akneriana and R. Dutemplei, are 

 scarcely, if at all, divisible from R. JJngeriana. All of these abound 

 in the present oceans. Another near modification of this form is 

 shown in the well-known Rlanorhulina (Truncatulina) lobatula, 

 Walker and Jacob, which also occurs in the Loudon Clay, though 

 not so plentifully as the foregoing, and frequents shallower water 

 than they do. 



* Cristellaria decorata, Reuss, Zeitsch. d. g. Ges. vii. pi. viii. fig. 66, and pi. xix. 

 tigs. 1, 2. 



