XX 
THE VOYAGE OF H.M.S. CHALLENGER. 
Silica, 
Hyperammina friabilis. 
93-63 
Eerric oxide, 
• . • , 
2-02 
Carbonate of lime, . 
. 
3-95 
99-60 
On the other hand, some of the smaller specimens of Hyperammina elongata have 
finely cemented tests, resembling Trochammina in their compact texture and smooth 
or sometimes polished exterior. 
Fragments of the gigantic Syringammina were found on analyses to contain more 
than 35 per cent, of carbonate of lime, notwithstanding the loose friable consistence of 
the test. Further examination, however, showed that this was due to the presence of 
large numbers of the minuter Foraminifera amongst the sand of which it was built, and 
not in any great degree to secreted calcareous matter. 
The chemical features of the Lituolidze have only been investigated so far as concerns 
two species, Haplophragmium latidorsatum 1 and Cyclammina cancellata, the analyses 
of which gave the following figures : — 
Haplophragmium 
Cyclammina 
latidorsatum. 
cancellata. 
Silica, .... 
76-1 
84-8 
Ferric oxide, with a little alumina, 
16-3 
9-4 
Carbonate of lime, 
7-3 
5-5 
99-7 
99-7 
The proportion of alumina in both cases was too small to be worth separate estima- 
tion, and was probably due to traces of adherent foreign matter. 
From these determinations it is evident that, in a considerable section of the arena- 
ceous genera, whether Astrorhizidjs or LiTUOLiDiE, the substance secreted by the animal 
for the incorporation of foreign bodies in the construction of the test, is composed of 
ferric oxide and carbonate of lime in variable proportions, the former being often in 
considerable excess. There are some cases, however, for example the large specimens 
of Reophax nodulosa described at page 294, in which after careful treatment with acids, 
under conditions to ensure the complete removal of ferruginous and calcareous constituents, 
the test is not disintegrated but retains its form, the sand-grains of which it is built 
still cohering with sufficient firmness to admit of the specimen being freely handled. 
Seeing that this occurs in dead and empty tests, it can scarcely be attributed to any 
remaining organic matter, so that it is probably due to the presence of small quantities 
of silica, free or combined, as an element of the cement. The fact that there are a 
few species which, in the absence of siliceous material, form their tests of calcareous sand, 
1 The Lituola subglobosa of M. Sars. 
