ORBICULINA. MILLIOLA. PLACENTULA. 143 
ORBICULINA. 
Shell sub-discoidal, multilocular ; whorls contiguous 
and compound ; spire eccentric ; chambers short, 
very numerous ; septa imperforate. 
O. uncInATA. W. 14. 58. 
MILLIOLA. 
Shell transverse, oval-globular or elongated, multi- 
locular ; chambers transverse, surrounding the 
axis, and successively covering one another; 
aperture very small, situated at the base of the 
last whorl, orbicular, or oblong. 
M. intortum. Mouth compressed, with a 
simple tooth attached to the proximal side, a 
little compressed ; the external margin sub-acute ; 
three chambers are usually visible on one side, 
and four on the other; slightly striated across, 
and the suture distinct. ;. B. W. 38. 2. 
PLACENTULA. 
Shell orbicular, convex above and below, multilocu- 
lar; aperture oblong, narrow, disposed as a ray 
in the inferior disc, or on both discs. 
P. asTERISANS. W. 13. 39. 
