652 
THE VOYAGE OF H.M.S. CHALLENGER. 
lobes or flaps, which give to the inferior face of the test its “ vesicular ” aspect. 
Under favourable conditions the shell attains a diameter of T I g th to T Uth inch (T4 
to 1'7 mm.). 
The Rotalia ( Discorbis ) gervillii of cl’Orbigny (Modele, No. 72) appears to be a 
compressed, thin-edged variety of the same species. 
Discorbina vesicularis has been taken at four Stations near the coast of New Guinea, 
namely : — Humboldt Bay, 37 fathoms ; Flinders Passage, 7 fathoms ; off Booby Island, 
6 to 8 fathoms ; and off Baine Island, 155 fathoms ; and at one point off the Fiji Islands, 
210 fathoms. It is common in the shore-sands of Melbourne, Australia (Parker and 
Jones), and of Tamatave, Madagascar. 
It occurs as a fossil in the Eocene of the vicinity of Paris (Lamarck, d’Orbigny), and 
in the Post-pliocene beds of Norway (Sars). 
Discorbina rugosa, d’Orbigny, sp. (PI. LXXXVII. fig. 3, a.b.c. ; PL XCI. 
fig. 4, a.b.c.). 
Rosalina rugosa , d’Orbiguy, 1839, Foram. Amer. Merid., p. 42, pi. ii. figs. 12-14. 
A more or less explanate modification of Discorbina, resembling Anomalina 
ammonoides in general contour. The test is compressed and exhibits some approach 
to bilateral symmetry, and the peripheral edge is round and lobulated. The umbilical 
cavity of the inferior side is partially covered in by the valvular flaps protecting the 
successive apertures. The drawings (PL LXXXVII. fig. 3) are taken from a typical 
example. A comparatively minute, compactly built variety, with more numerous and less 
ventricose segments, is represented in Pl. XCI. fig. 4. 
Discorbina rugosa has been obtained from two Stations on the southern shores of 
Papua, namely, — off Raine Island, 155 fathoms ; and off Ki Islands, 580 fathoms. The 
locality quoted by d’Orbigny is the Bay of St. Bias, Patagonia. 
Discorbina poly stomelloides, Parker and Jones (Pl. XCI. fig. 1 , a.b.c.). 
Discorbina / polystomelloides, Parker and Jones, 1865, Phil. Trans., vol. civ. p. 421, pl. xix. 
fig. 8, a.b.c. 
This strongly-marked species is stated by Parker and Jones to be “ a granulose form 
of Discorbina rimosa, but larger, more symmetrical, and extremely rough ; and the 
chinks between the chambers partly bridged over, so as to form a rough canal system, as 
in some of the Polystomellce.” The diameter of some of the Challenger specimens is 
fully x ] 5 th inch (l ’68 mm.). 
