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THE VOYAGE OE H.M.S. CHALLENGER. 
In the structure of its test, the large fusiform Miliola of the coral-reefs differs equally 
from the normal forms with homogeneous shell-wall and smooth exterior, and the 
coarsely arenaceous types. Its minute texture, as shown in the longitudinal section 
(fig. 18), is that of a thin imperforate porcellanous layer with embedded sand-grains ; the 
siliceous grains being generally rather more numerous than appear in the figure, as some 
are unavoidably lost in process of making a section. The young shell somewhat 
resembles Miliolina saxorum in general contour, but the segments are more discrete and 
rounded, and even in the very early stage, whilst the surface is but slightly arenaceous, 
the species is easily identified. The cribrate aperture is a character of the genus 
Hauerina, rather than of the true Miliola ?; there are, nevertheless, important exceptions, 
such as Miliolina saxorum, Lamarck, and Miliolina ( Quinqueloculina ) fabularioides, 
Karrer, in which the porous condition of the orifice is a distinctive feature. In the 
present species the orifice is often so obscured by sand-grains as to be scarcely 
discernible. 
Miliolina alveoliniformis is essentially a coral-reef species. So far as has been 
noticed hitherto, it is not very abundant in any single locality, but is of moderately frequent 
occurrence in littoral and shallow- water sands — that is to say, at depths of less than 50 
fathoms — amongst the islands of the Pacific, in the Red Sea, and in the West Indies. 
That its bathymetrical range is not strictly limited to the shallower zones is indicated 
by the occurrence of a few specimens in a sounding from a depth of 420 fathoms, off 
Tahiti. 
Sub-family 3. Hauerininee. 
Articulina, d’Orbigny. 
Nautilus, pars, Gmelin [1788], Batsch. 
Articulina, d’Orbigny [1826], Bronn, Reuss. 
Vertebralina, pars, Parker, Jones, and Brady [1865], Karrer. 
The genus Articulina comprises a group of dimorphous Miliolcr, in which the typical 
Triloculine or Quinqueloculine arrangement of the chambers prevails during early life, 
but subsequently gives place to a rectilinear mode of growth. The relative development 
of the two portions of the shell varies much more in Articulina than in Vertebralina. 
In certain species the linear chambers are never conspicuously developed, and the affinity 
can only be determined by the contour of the Milioline segments and the form of the 
aperture ; in some, the linear portion consists of only one or two segments ; whilst in 
others the test is a long Nodosaria-like line of chambers, in which the Milioline 
characters are confined to a small bulbous or knot-like swelling at the primordial end 
of the shell. The aperture of Articulina is usually situated in a deep bordered depression 
