724 
THE VOYAGE OE H.M.S. CHALLENGER. 
kingdom is a matter of controversy. It is regarded by Dawson and Carpenter as a 
massive sessile Foraminifer, composed of acervuline layers, and endowed with a supplemen- 
tary skeleton and a system of ramifying canals. 
Sub-family l. Fusulininse. 
This Sub-family has no living representatives, the species which it embraces being 
fossils, for the most part of Carboniferous age. 
Sub-family 2. Polystomellinse. 
Nonionina, cTOrbigny. 
Nautilus, pats, Walker and Boys [1784], Adams, Walker and Jacob, Fichtel and Moll, Montagu, 
Maton and Rackett, Pennant, Turton, Wood, Fleming. 
Chry solus, Florilus, Nonion, Montfort [1808]. 
Melonis, Montfort [1808], Blainville. 
Pulvinulus, pars, Lamarck [1816]. 
Placentula, pars, Lamarck [1822], 13 ef ranee. 
Cristellaria, pars, Lamarck [1822]. 
Lenticulina, pars, Defrance [1824], Blainville. 
Polystomella , pars, Defrance [1824], Blainville, Macgillivray, Thorpe, Parker and Jones. 
Nonionina, d’Orbigny [1826], Roemer, Bronn, Reuss, Czjzek, Alth, Williamson, Costa, Parker 
and Jones, Egger, Karrer, Giimbel, Carpenter, Seguenza, Brady, M. Sars, Alcock, 
Dawson, &c. 
The genera Nonionina and Polystomella constitute a single series of gradational 
forms so closely linked from end to end that even the separation into two subordinate 
groups is attended with certain difficulties. The general conformation and arrangement 
of the test are the same in both genera. It is composed of numerous segments combined 
in an equilateral nautiloid spire, the latest convolution of which completely encloses 
those preceding it ; and the aperture is either an arched fissure or a row of pores placed 
symmetrically at the inner margin of the terminal segment, close to the line of union 
with the previous convolution. The walls are hyaline and distinctly, though often very 
finely, foraminated. 
To the Nonionine group are assigned the simpler members of the series, — those, 
namely, which exemplify the foregoing with but few additional features. 
There is, however, one point in the structure of the more typical Nonionina which it 
is needful to notice ; and that is the tendency exhibited by certain species to develop 
exogenous lines of shell-substance, of greater or of less length and thickness, in the septal 
depressions, near the centre of the test. This “sutural limbation” is an exceedingly 
variable feature. There are certain species in which it is absent or hardly discernible ; 
