650 
THE VOYAGE OF H.M.S. CHALLENGES. 
Discorbina opercularis, d’Orbigny, sp. (PL LXXXIX. figs. 8, 9). 
Rosalina opercularis, d’Orbigny, 1826, Ann. Sci. Nat., voL vii. p. 271, No. 7. 
„ „ Id. 1839, Foram. Cuba, p. 101, pi. iii. figs. 24, 25 ; pi. iv. fig. 1. 
Discorbina opercularis, Parker and Jones, 1872, Quart. Journ. Geol. Soc., vol. xxviii. p. 114. 
A thin, depressed, convex or subconical variety, the superior face exhibiting two to 
three convolutions with very numerous, narrow, arcuate segments ; the inferior face 
ornamented with faint riblets or tubercles. 
This form has been observed at four points on the coast of Australia, namely : — off 
Paine Island, Torres Strait, 155 fathoms; off East Moncoeur Island, Bass Strait, 38 
fathoms; Port Jackson, 2 to 10 fathoms; and Curtis Strait, Queensland ; and also, ac- 
cording to d’Orbigny, in the shore-sands of Cuba and Martinique, West Indies. 
Discorbina pulvinata, n. sp. (PL LXXXVIII. fig. 10, a.b.). 
Test broadly ovate or subglobular, somewhat depressed ; composed of a few more or 
less inflated segments, about three in the final convolution ; superior face rugose ex- 
ternally ; inferior deeply excavated at the umbilicus and ornamented with radiating 
granulose lines. Diameter, -g\,th inch (0'28 mm.). 
The foregoing provisional description is intended to characterise an obscure obese 
variety of Discorbina which does not appear to be otherwise provided for. Its nearest 
ally is perhaps the Discorbina platyomphala of Eeuss (Sitzungsb. d. k. Ak. Wiss. Wien, 
1867, vol. lv. p. 102, pi. iv. fig. 13).. 
The specimens were found in anchor-mud from Nares Harbour, Admiralty Islands, 17 
fathoms ; and off Booby Island, south of Papua, 6 to 8 fathoms. 
Discorbina bertheloti, d’Orbigny, sp. (Pl. LXXXIX. figs. 10-12). 
Rosalina bertheloti, TOrbigny, 1839, Foram. Canaries, p. 135, pl. i. figs. 28-30. 
Discorbina bertheloti, Brady, 1864, Trans. Linn. Soc. Lond., vol. xxiv. p. 469, pl. xlviii. 
fig. 10, a.b. 
,, turbo, var. parisiensis, subvar. berthelotiana, Parker and Jones, 1865, Phil. Trans., 
vol. civ. p. 387, pl. xvi. figs. 26, 27. 
Discorbina bertheloti has a thin outspread test, of which the more distinctly spiral 
face is flat or nearly so ; the reverse side convex. It is isomorphous with the more 
depressed varieties of Truncatulina lobatula, from which it may generally be known by 
its somewhat large final segment and its thinner and more finely perforated walls. 
Though nowhere very common, Discorbina bertheloti is widely distributed. A list of 
from twenty to thirty localities embraces points in the Arctic Ocean, the North and 
South Atlantic, the North and South Pacific, and the Mediterranean, — the northernmost 
being on the shores of Novaya Zemlya, the most southerly at the south-eastern corner of 
Australia. The home of the species is at depths of less than 500 fathoms, but occasional 
