REPOET ON THE FORAMINIFERA. 
745 
formations, such as the Miocene of Dax near Bordeaux, and of Jamaica, and the Crag of 
Sutfolk. 
Operculina ammonoides, Gronovius, sp. (PL CXII. figs. 1, 2). 
Nautilus ammonoides, Gronovius, 1781, Zooph. Gron., p. 282, No. 1220, and p. v. 
„ balthicus, Schroeter, 1783, Einleitung, vol. i. p. 20, pi. i. fig. 2. 
Operculina complanata, Parker and Jones, 1857, Ann. and Mag. Nat. Hist., ser. 2, vol. xix. 
p. 285, pi. xi. figs. 3, 4. 
Nonionina elegans, Williamson, 1858, Rec. Eor. Gt. Br., p. 35, pi. iii. figs. 74, 75. 
Operculina ammonoides , Parker and Jones, 1862, Introd. Eoram., Appendix, p. 810. 
Nummulina perforata, var. ( Operculina ) ammonoides, Parker and Jones, 1865, Phil. Trans., 
voL civ. p. 398 ; pi. xiv. fig. 44 ; pi. xvii. figs. 62, 63. 
Nonionina elegans, Fischer, 1870, Actes Soc. Linn. Bordeaux, vol. xxvii. p. 396, No. 45. 
This is a starved variety, the test of which is of comparatively small dimensions, but 
proportionately thicker than that of typical Operculina complanata ; and it is further 
characterised by having strongly limbate sutures. The diameter seldom much exceeds 
^th inch (0‘56 mm.). 
Operculina ammonoides is not uncommon at moderate depths on the shores of 
Norway, Denmark, Great Britain, and France. It occurs at fourteen “ Porcupine ” 
Stations and one Challenger Station in the North Atlantic, at depths of 45 to 1630 
fathoms, the most southerly point being off the Canaries. It has also been observed in the 
Mediterranean, 320 fathoms, and in the Gulf of Suez, 30 fathoms ; off the Cape of Good 
Hope, 150 fathoms; on the coast of Australia, 17 fathoms; at three points south of 
Papua, 129 to 800 fathoms; off the Philippines, 95 fathoms; in Hong Kong Harbour, 
7 fathoms ; and south of Japan, 345 fathoms. 
It was one of the Foraminifera obtained by the late Prof. M. Sars from the Post- 
tertiary beds of Norway, and it is mentioned doubtfully by Seguenza amongst the Pliocene 
fossils of Calabria. 
Heterostegina, d’Orbigny. 
Heterostegina , d’Orbigny [1826], Bronn, Reuss, Riitimeyer, Carpenter, Jones and Parker, Carter, 
Karrer, Kaufmann, Giimbel, Hantken, Brady, Moebius, Seguenza, &c. 
The test of Heterostegina bears a general analogy to that of Opercidina. It has the 
same external contour, and attains like dimensions ; and the chambers though differing 
in certain points are arranged on a similar plan. The primary distinction between the 
two genera rests upon the fact that whilst the chambers of Operculina are simple and 
entire, those of Heterostegina are subdivided by transverse septa into chamberlets. In 
other words, the mutual relationship of Operculina and Heterostegina is precisely that 
which exists between Peneroplis and Orbicidina, amongst the porcellanous types. 
The subdivision of the chambers, however, gives rise to a well-marked difference in the 
