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 comprcssed^ 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, yq. 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. 



