AMPHISTEGINA VULGARIS. 359 



Sub-family 2. — Nummulitin^!. 

 Brady, ' Challenger ' Report, 1884, p. 75. 



Test lenticular or complanate ; lower forms with thickened and finely tubulated 

 shell-wall, but no intermediate skeleton ; higher forms with interseptal skeleton 

 and complex canal-system. 



Genus 1. — Amphistegina, d'Orbigny, 1826. 



Carpenter, Phil. Trans., vol. cxlix, 1859, pp. 30 — 35; Introd. Foram., 1862, ^?p. 241 

 —247, pi. xciii, figs. 22—29 ; Brady, Report ' Challenger,' 1884, pp. 75 and 739. 



Amphistegina, d'Orbigny, Bronn, von Beuss, Boemer, Cuvier, Bidet, Suess, 

 Williamson, Ehrenberg ■, Carpenter, Barker and Jones, Karrer, 

 Bourtales, Kaufmann, Mobius, Brady, Abich, von Oiimbel, 

 Terquem, BLarting, Bunzel (. ? ), von Zittel, Schwager, Credner, 

 de Lapparent, de Amicis, Nicholson, Biitschli, Steinmann, 

 Terrigi, Smedley, Bassett, Kblliker, Chapman, and others. 



Heterostegina, Nonionina, Ehrenberg. 



Hemistegijta, Kaufmann. 



General Characters. — Shell free, lenticular, umbonate, inequilateral, more 

 convex on one side than the other ; consisting of a turbinoid spire, each convolu- 

 tion completely embracing the previous whorl. Chambers saddle-shaped (equitant), 

 the alar prolongations on the upper side simple (as in Nummulites), on the lower 

 divided each into two portions by the constriction of the sarcode ; the secondary 

 lobes being directed backwards and radially, and being intercalated have the 

 appearance externally of an independent whorl of chambers. Aperture on the 

 lower side of the ultimate chamber (as in the Rotalinse). 



The structural peculiarities of the genus Amphistegina are treated at length in 

 Dr. Carpenter's 'Introduction,' &c, p. 241, et seq. 



Amphistegina vulgaris, d'Orbigny, 1823. Plate II, figs. 46 — 48. 



Part I, 1866, Appendix I, Table, No. 92; Appendix II, Table, No. 91. 



Lenticuia, Soldani, 1780. Sagg. Oritt., p. 106, pi. iv, figs. 32 e, E ; and pi. vii, 



figs, zz, ZZ(?) ; Testaceogr., vol. ii, App., p. 140 

 (Ammonia), and p. 141 (same pi. and figs.). 



