58 FORAMINIFERA OF THE CRAG. 



of Nodosarim, and hybrid individuals being almost as common as any of the so-called 

 typical varieties. 



BentalincB vpith a central apertiu^e (PI. I, fig. 9, for instance) are merely bent 

 Nodosarice. When the aperture is excentric, and the shell is tapering and curved, vpe 

 have a " Dentalina " if it be round in transverse section, and " Vaginulina " if it be 

 compressed. But often a shell is Yaginuline (compressed) in its early growth and 

 Dentaline when old, and this is the case with fig. 10, a Dentaline form of Vaginulina 

 linearis. The compressed forms are often straight, and therefore most of the VaginulincB 

 are straight rather than curved. If in a compressed shell, stouter than the tapering 

 forms, and commencing with a relatively larger segment, or with coiled segments, the 

 septal apertures follow the convex margin, we have a " Marginulina" (fig. 36) ; and a stout 

 Nodosarian shell, circular in section, and wdth its septal apertures marginal, is also a 

 " Marginulina" (PI. I, fig. 21). If, however, these straight, stout, oblique-chambered 

 Nodosarince, with marginal aperture, be much compressed at the edges (being then acute- 

 oval in transverse section), they pass as VaginulincB (PI. IV, fig. 9). 



It is very difficult, therefore, to place all straight Nodosarian specimens definitely in 

 one or other of these groups, which are quite artificial ; for Marginuline and Dentaline 

 forms of Nodosaria raphanus (compare PI. I, figs. 4, 9, 19, 21) and similar conditions of 

 N. radicida abound, wandering from Glandulincs and Lingulince to Cristellaries, 

 MahellincB, &c., without any real zoological distinction. 



Dentalina communis, D'Orbigng. 



a. With straight se2}tal jilanes. Plate I, figs. 13—18, 20 ; Plate IV, fig. 10. 



Nautilus (Orthoceras) leguminiformis (parte), Batsch, 1791. Conch. Seesand., 



pi. 3, fig. 8 b. 



— RECTUS, Montagu, 1808. Test. Brit. Supplem., p. 82, pi. 19, figs. 4, 4', 7. 

 Nodosaria dentalina, Lamarck, 1822. Anim. sans Vert., vol. vii, p. 596, No. 2. 



— ^.MWdKTk, Nilsson, 1825. Act. Acad. Holm., 1825, p. 342 ; 1827, Petrif. 



Suec, p. 8, pi. 20, fig. 20. 



— (Dentalina) communis, D'Orb., 1826. Ann. Sc. Nat., vol. vii, p. 254, 



No. 35 ; after Soldani, Testae, vol. ii, pi. 105, 

 fig. o. (Montagu's N. rectus is catalogued by 

 D'Orbigny as var. a of this species.) 



— LiEviGATA, Hisinger, 1837. Lethsea Suecica, p. 33. 



— (Dentalina) gracilis, D'Orb., 1840. Mem. Soc. Geol. France, vol. iv, 



p. 14, pi. 3, fig. 5. 



— — NODOSA, Id. lb., figs. 6, 7. 



— LORNEIANA, Id. lb., figs. S, 9. 



— LINEARIS, Boemer, 1840. Verst. Nordd. Kreid., p. 95, pi. 15, fig. 5. 



