384 
MOLLUSCA. 
and alternately surmounting each other; aperture very small, 
orbicular or oblong, situated at the base of the last volution. 
Miliola ovata .— The Oval Miliola. 
Plate LXXXIII. fig. 18. 
Ovate, small, with an oblong-ovate aperture. Fossil at 
Grignon. 
TRIBE V.-CRISTACEA. 
Shell semidiscoid, with an eccentric spire. 
Genus 23. —ORBICULINA. — Lamarck. 
Generic Character. — Shell subdiscoid, multilocular; spire 
eccentric; volutions contiguous and compound ; chambers short 
and numerous *, septa imperforate. 
Orbiculina uncinata .— The One Sinused Orbiculina. 
Plate LXXXIII. fig. 19. 
Spirally striated, and the volutions separated by a deep sinus. 
Fossil. 
Genus 24.—CRISTELLARIA.— Lamarck. 
Generic Character. —Shell semi-discoidal, multilocular; cham¬ 
bers contiguous and simple, progressively enlarging ; spire eccen¬ 
tric, subulate; septa imperforate. 
Cristellaria squammula. — The Scaled Cristellaria. 
Plate LXXXIII. fig. 20. 
Shell externally covered with minute scale-like marks. Fossil. 
Genus 25.—RENULINA— Lamarck. 
Generic Character. —Shell kidney-shaped, flat, sulcated, and 
multilocular ; volutions linear, contiguous, the second curved, 
the last lengthened; the axis marginal. 
Renulites opercularis _ The Lid-Shaped Renulina. 
Plate LXXXIII. fig. 21. 
Semilunar flat, with arcuated concentric rijdges. Fossil at 
Grignon. 
