NARRATIVE OF THE CRUISE. 
835 
foreshadowed by the researches of Major Owen and others, has been placed on a broader 
and more intelligible footing by the discovery of numerous species in the surface water 
which, were previously supposed to inhabit exclusively the bottom ooze. Furthermore, 
the whole subject of recent oceanic deposits and the organisms concerned in their pro- 
duction, of which the Foraminifera are amongst the most important, may almost be said 
to owe its initiation to data collected during the Challenger cruise. 
“All the larger groups of Foraminifera have been enriched to a greater or less degree 
by the results of the Expedition. Amongst the Porcellaneci, or those forms which are 
provided with an imperforate calcareous skeleton, the most noteworthy acquisitions, 
so far as the simpler types are concerned, are certain species referrible to Seguenza’s 
genus Planispirina. This genus, which was first fully described by Steinmann under 
the name Nummoloculina, is characterised by the laminated structure of the shell, 
caused by the extension of the umbilical margins of the chamber- walls over the lateral 
Fig.- 304 . — Cymbolopom ( Tretomphalus ) bulloides (d’Orbigny). 
a, Large surface-specimen ; b, small (young ?) specimens from the same gathering ; c, distal face of the balloon-like 
chamber, showing the entosolenian orifice, seated in a slight depression. All magnified 60 diameters. 
faces of the test, a feature which it possesses in common with the much more highly 
organised type, Nummulites. The specimens of the genus Orbitolites, collected chiefly 
on the reefs of the Fiji and the Friendly Islands, have afforded ample groundwork 
for the revision of the structural and geological relations of that somewhat complex 
generic group . 1 
“ Of even greater interest and importance is the discovery of the new porcellanous 
type Keramosplicera, in a Diatom ooze obtained from deep water in the Southern Ocean. 
This organism, the structure and position of which have been made the subject of a 
special ‘Note’ by Mr. Brady , 2 is closely allied to Orbitolites, and, in a less marked 
degree, to Alveolina. The shell is spherical and composed of a multitude of chamberlets 
1 Report on the specimens of the genus Orbitolites, by W. B. Carpenter, C.B., F.R.S., Zool. Chall. Exp., part xxi., 
1883. 
2 Ann. and Mag. Nat. Hist., ser. 5, vol. x. p. 242, pi. xiii., 1882. 
