REPORT ON THE FORAMINIFERA. 
653 
Discorbinci polystomelloides occurs at three Stations amongst the islands south of New 
Guinea, namely off Booby Island, 6 to 8 fathoms; off Wednesday Island, 8 fathoms; 
and Flinders Passage, 7 fathoms. The locality given with the original description is 
the Australian coral-reefs. 
Discorbina biconcctvci, Parker and Jones (PI. XCI. figs. 2, 3). 
Discorbina biconcava, Parker and Jones, 1865, Phil. Trans., vol. civ. p. 422, pi. xix. fig. 10, 
a.b.c. 
„ „ Siddall, 1878, Proc. Chester Soc. Nat. Sci., pt. 2, p. 50. 
This species is described by Parker and Jones ( loc . cit.) as “ a very small isomorph of 
Planulinci ariminensis; a hyaline, thick, limbate, square-edged, biconcave Discorbina, 
most concave on the umbilical face, and with feeble astral flaps.” 
The small size is an occasional rather than an invariable feature, for under favour- 
able circumstances the test attains nearly the same dimensions as that of Anomalina 
{Planulina) ariminensis. The sutural limbation of small shells (fig. 3) is often confined 
to the inferior face. 
Discorbina biconcava has been met with at three Challenger Stations, all of them on 
the coast of Australia: — off East Moncceur Island, Bass Strait, 38 fathoms; Port 
Jackson, 2 to 10 fathoms ; and off Kaine Island, Torres Strait, 155 fathoms. Prof. 
Parker’s specimens were found in shore-sand from Melbourne, and in my own cabinet 
there are good examples from Storm Bay, Tasmania. Mr. J. D. Siddall has minute but 
well characterised shells from the estuary of the Dee ; and but for this fact, the 
species might be supposed to belong exclusively to Australia and the neighbouring 
islands. 
Discorbina saulcii, d’Orbigny, sp. (PI. XCI. fig. 6, a.b.c.). 
Rosalina saulcii, d’Orbigny, 1839, Foram. Am£r. Merid., p. 42, pi. ii. figs. 9-11. 
Discorbina saulcii, Parker and Jones, 1872, Quart. Journ. Geol. Soc., vol. xxviii. p. 156. 
The general contour of the test forms perhaps the most distinctive specific feature of 
Discorbina saulcii, the superior or spiral face being flat, the inferior or apertural side 
convex, and the peripheral edge subangular or rounded. The length and degree of 
curvature of the segments, as seen on the superior side, are subject to considerable varia- 
tion ; and in most of the specimens which have come under my notice they are longer, 
narrower, and more bent than depicted by d’Orbigny. The degree of development of the 
umbilical lobes is also very different in different shells, the central vestibule being 
sometimes completely closed, as indicated by the original drawings, but more frequently 
only partially occupied, leaving a deep umbilical cavity (fig. 6, b). Variability in this 
(ZOOL. CHALL. EXF. PART XXII. 1884.) Y 83 
