NONIONINA. 337 



Genus 1. — Nonionina, cVOrbigny, 1826. 

 Carpenter's Introcl. For am., 1862, p. 286; Brady, ' Challenger ' Report, p. 724. 



Synonyms : 



Nautilus, Linne, Gmelin, Adams, Walker and Jacob, Soldani, Fichtel and Moll, 

 Montagu, Maton and Rackett, Pennant, Turton, Wood, Fleming, 

 Dillwyn, Brown. 



Nautilites, Soldani. 



Cheysolus, Floeilus, and Nonion, de Montfort. 



Melonis, de Montfort, Blainville. 



Pultinulus, Lamarck. 



Placentula, Lamarck, Defrance. 



Cbistellaeia, Lamarck. 



Lenticulina, Defrance, Blainville. 



Poltstomella, Defrance, Blainville, Macgillivray, Thorpe, Parker and Jones. 



Robulina, d'Orbigny. 



Aeisteeospiea, Ehrenberg. 



Noniostina, d'Orbigny, Sander Rang, Menke, R'omer, Bronn, Reuss, Czjzek, Alth, 

 Risso, Williamson, Ehrenberg, Costa, Parker and Jones, Egger, 

 Karrer, von Oiimbel, Carpenter, Seguenza, Brady, M Sars, Alcock, 

 Dawson, Millett, Parfitt, Woodward and Thomas, Terrigi, Forna- 

 sini, von Hantken, Terquem, Goes, Schwager, Andreae, Balkwill and 

 Wright, A. Silvestri, and others. 



General Characters. — Shell free; spiral, equilateral. Inner convolutions nearly 

 or entirely concealed by the outermost whorl. Septa, in well-developed forms, 

 thickened at and near the umbilicus by a granulate or stellate deposit of exogenous 

 shell- substance. Aperture single, curved, slit (normally simple), on the inner 

 edge of the terminal chamber. 



Supplemental skeleton either absent or rudimentary, and confined to the 

 umbilical region. No external septal pores nor bridges, except in some transitional 

 individuals. 



Mr. F. W. Millett has kindly supplied the following systematic list or scheme 

 of the Nonioninae, arranged gradationally, and based chiefly upon the condition of 

 the umbilical region (pp. 339 — 341). It shows how the tendency to exogenous 

 growth increases with the inflation of the chambers, and the consequent lobulation 

 of the periphery characteristic of one of the types, N. depressula. The scheme is 

 of course defective, as it refers only to published figures. It might be greatly 

 improved by a careful examination of specimens in good collections. 



The affinities of the species of the Foraminifera are so complex that it is 



