250 
THE VOYAGE OF H.M.S. CHALLENGER. 
interior smooth ; with minute interstitial orifices, but no general aperture. Colour 
reddish-brown. Diameter, from xiroth to jtth inch (0'16 to 4'0 mm.). 
This is one of the simplest of the arenaceous Foraminifera. Although by no 
means uncommon in deep water, it remained undescribed until the publication of Prof. 
Schulze’s memoir above quoted. Fifteen years or more ago I found it in considerable 
abundance in one of the “ Bulldog ” soundings obtained by Dr. Wallich, but the 
specimens were very minute, and in the then existing state of knowledge it was difficult 
to decide whether they were Foraminifera or not. It has been the custom to consider 
that the tests of the arenaceous Ehizopoda are of necessity imperforate ; in other words, 
that except the general pseudopodial orifice the investment is non-porous, and the fact of 
these specimens having no general aperture created a doubt as to their Foraminiferal 
character. But it is now well understood that the term “ imperforate ” is only applicable 
to a limited number of genera, and that some at least of the sandy forms have more or 
less porous tests, though, owing to their composite texture and the irregularities of the 
surface, the orifices are but little apparent on the exterior. 
Schulze’s description of the species is quite accurate as applied to large specimens. 
They are spheroidal bodies, from two to four mm. (yVth to jtth inch) in diameter, 
without any perforations visible to the naked eye, commonly free, but occasionally 
adherent to small stones. The test itself is from ‘25 to ’5 mm. thick, and is composed 
of coarse sand-grains, united by a cement of fine texture and of characteristic grey-brown 
colour. Whilst the exterior is more or less rough, owing to projecting sand-grains or 
fragments of stone, the interior is throughout even and smooth (PL XVIII. fig. 6), the 
constituent angular particles being very neatly fitted together and cemented. But in 
point of size the range is much wider than that suggested by the large North-Sea 
specimens, and in some areas adult and otherwise characteristic tests scarcely average 
x^-yth of an inch in diameter, and are often much smaller. 
The tendency of the animal to attach itself to foreign bodies is revealed in many 
different ways ; sometimes a fragment, but little smaller than the remainder of the test, is 
built into the wall ; in other cases the shell is erected, tent-like, upon a stone. In several 
localities minute specimens like that represented in PI. XVIII. fig. 4, built upon or 
around a sponge-spicule, are very common. Occasionally where the species is abundant 
the spheres are found adhering to each other, and forming what appears at first sight a 
polythalamous test (PI. XVIII. fig. 8). It is evident, however, that the connection is 
purely accidental, and examples do not occur with sufficient frequency to warrant the 
idea that there is any tendency to associate in colonies as in Sorosphcera. 
It is somewhat remarkable that, notwithstanding the thickness of the test and its 
rough composite texture, these sandy spheres are quite translucent when fresh, and 
retain this character for a long period, when preserved in glycerine or diluted alcohol. 
