24 FORAMENIFERA. RENULINA. 
with a central spire ; volutions contiguous, enveloping, tuni- 
ciform; cells narrow and numerous ; septa imperforate. 
Melonia spheroides. Pilate II. fig. 22. 
Genus VIII. — GYROGONA. — Lamarck. 
Generic Character. — Shell spherical, concave within, 
composed of linear, curved, canaliculate pieces; exter- 
nal surface with carinated, parallel, partly transverse ribs, 
and bound at the last volutions ; aperture round, terminated 
by a small round shell. 
Gyrogona costuta. Plate IL. fig. 24. 
D’Orbigny has instituted three genera, which he conceives connected with 
the present family. They are extremely obscure, and as we are informed by 
De Blainville, that he has ascertained from observations that the animals have 
no tentacula, they must be greatly removed from this family. We have 
merely figured them without attempting generic characters. They are, 
1. Quinguiloculina striatula. Plate IL. figs. 21 and 25, 
2. Triloculina communis. Plate II. figs. 12 and 19. 
3. Biloculina opposita. Plate IL. figs. 20 and 28. 
TRIBE IV.— CRISTACEA. 
Shell semidiscoidal, multilocular, with an eccentric spire. 
Genus 1X. — ORBICULINA. — Lamarck. 
Generic Character. — Shell sub-discoidal, multilocular, 
with compound contiguous volutions ; spire eccentric; cells 
short, very numerous ; septa imperforate. 
Orbiculina uncinnata. Plate II. fig. 31. 
Genus X.— CRISTELLARIA. — Lamarck. 
Generic Character. — Shell semidiscoidal, multilocular, 
with contiguous simple, progressively enlarging cells; spire 
eccentric, sublateral ; septa imperforate. 
Cristellaria squammula. Plate II. fig. 27. 
These minute species are found both in a fossil and recent state. 
Genus XI.— RENULINA. — Lamarck. 
Generic Character. — Shell reniform, flattened, multilo- 
cular, sulcated, with linear contiguous volutions, curved 
round a marginal axis, the most distant from the axis being 
the longest. 
Renulina opercularia. Plate II. fig. 34. 
