46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. '/'] 



Genus ENDOTHYRA Phillips, 1846 



Test calcareous, composed of an outer coarsely perforated layer 

 and inner finely granular, compact layer, chambers numerous, in an 

 irregular spiral coil, aperture of several rounded openings. 



Genus ROTALIATINA Cushman, 1925 



Test free, trochoid, spiral, composed of about three volutions, the 

 last one composed of numerous chambers, all the chambers exposed 

 from the dorsal side, only those of the last-formed coil visible from 

 the ventral side, umbilicate ventrally ; chambers distinct ; sutures dis- 

 tinct and usually slightly depressed ; wall in the known species smooth ; 

 aperture an arched slit between the base of the apertural face and the 

 previous coil. 



Genus ROT ALIA, Lamarck, 1804 



Plate 12, fig. 2 



Test free, composed of numerous chambers arranged in a flattened 

 spire, the two sides biconvex or varying from flat above and convex 

 below to convex above and flattened below ; all chambers visible from 

 the dorsal side, only those of the last-formed coil visible from below ; 

 the umbilical region usually filled with clear shell material ; surface 

 variously ornamented with raised bosses or costje or smooth and 

 unornamented ; aperture a single curved opening toward the periphery 

 on the ventral side of the chamber. 



Genus CALCARINA d'Orbigny, 1826 

 Plate 12, fig. 3 



Test composed of numerous chambers, close coiled, biconvex ; 

 periphery usually with radiating spines ; chambers visible at least 

 on the ventral side, sometimes on the dorsal side as well ; aperture 

 typically consisting of a row of small openings along the inner margin 

 of the apertural face ; supplemental skeleton and canal system highly 

 developed. 



Genus SIDEROLITES Lamarck, 1801 

 Plate 12, fig. 4 



Test with early chambers close-coiled, Rotaliform, later with numer- 

 ous chambers, a few large spines running from the early chambers 

 to the exterior and thence outward ; aperture at the base of the last- 

 formed chamber, later in the large perforations of the chamber. 



