Nomenclature of the Foraminifcra. 347 



referring to Walker's Jig. 69 (erroneously) and to Montagu's 

 pi. 18. tig. 1, as the same form. Walker's fig. 68 (Nouionina 

 depressula) is the variety nearest to Montagu's figured specimen. 



Intending to take Nonionina crassula ("Walker and Montagu) 

 as the specific type, we have noticed under this name a little 

 Nonionina from Norway, in the Ann. N. H. 1857, xix. p. 286; 

 but we believe that the form described by Fichtel and Moll as 

 Nautilus asterisans best represents the essential characters of the 

 specific group to which Non. depressula, Walker, Non. crassula, 

 Walker, Non. umbilicatula, Montagu, Non. incrassata, F. & M., 

 and many other varieties belong. The Norwegian form above 

 referred to will therefore stand w T ith us as Nonionina astei-isans, 

 F. & M., var. umbilicatula, Mont. 



(E. b.) P. 191, and Supplem. pi. 18. f. 2, p. 79. "Nautilus 

 crassulus." This is the same as Walker's fig. 70, and is a va- 

 riety of Nonionina asterisans, F. & M. sp., which is a form having 

 an extreme variability of outline and of thickness. The septal 

 lines maybe flush with the chamber- walls, or sulcate, or limbate 

 in many modifications. In this specimen from Reculver we 

 have an open umbilicus and sulcate septal lines, both in greater 

 degree than in the former variety, pi. 18. fig. 1. 



Similar varieties of this Nonionina abound in shallow seas, 

 and are among the few Foraminifera that live high up in estua- 

 rine waters and in salt-marshes. The Foraminifera represented 

 by pi. 18. figs. 1-6, and fig. 9 in pi. 14 [Nonionina umbilicatula, 

 N. crassula, Rotalia inflata, R. Beccarii, Polystomella crispa, 

 and Triloculina oblonga) are the group especially affecting these 

 habitats. 



(F.) Supplem. pi. 18. f. 3, p. 81. " Nautilus infiatus." This 

 is a Rotalia of a typical specific fonn (as already remarked by 

 Williamson), and characteristic of a subgenus. This sandy- 

 shelled Rotalia, exhibiting a structural condition rare, if not 

 unique, among the genus, differs from its congeners so strikingly 

 in this particular, and in its almost globigerine mode of growth, 

 that we propose to refer it to a separate subgenus under the 

 name Trochammina*. 



The species under notice, which has always an arenaceous 

 shell, has its fullest development in shallow water, where it is 

 sometimes very abundant. For instance, some of the clay from 

 the Peterborough Fens yields it profusely. Montagu had it 

 from Devon, and Prof. Williamson has found it elsewhere on 

 our coasts ; usually it is rare. It occurs also at Leghorn. In 

 deeper water it is represented by attenuated varieties, ultimately 

 becoming Spirilline. The contrary to this habit holds good with 



* From rpoxos, rota ; and a^ixos, arena. 



