NO. 4 FOR.\MIXIFERA CUSHMAN 43 



Family 8. ROTALIIDAE 



Test calcareous, perforate, composed usually of numerous cham- 

 bers, except in the subfamily Spirillininae, early chambers coiled, 

 and later chambers in typical genera spirally coiled so that the cham- 

 bers are all visible from the dorsal side and only those of the last 

 formed coil from the ventral side, convexity of the two sides vary- 

 ing greatly ; later development in specialized genera being columnar 

 or even arborescent. 



Subfamily i. SPIRILLININAE 



Test free or attached, composed of a proloculum and a long coiled 

 tubular second chamber ; variously ornamented ; aperture at the end 

 of the tube ; wall calcareous, perforate. 



Genus SPIRILLINA Ehrenberg, 1841 



Plate 8, fig. 10 



Test typically free, occasionally attached, spiral, composed of a 

 subcircular or ovoid proloculum and a long undivided tubular second 

 chamber, coiled regularly in one plane ; wall hyaline and perforate ; 

 surface smooth or variously ornamented ; aperture formed by the 

 open end of the tube. 



Subfamily 2. ROTALINAE 



Test spiral, rotaliform, rarely evolute, very rarely irregular or 

 acervuline ; chambers numerous, distinct or in some few species 

 largely obscured by shell growth, early chambers in all distinctly 

 rotaliform. 



Genus PATELLINA Williamson, 1858 

 Plate 9, fig. 4 



Test conical in form or plano-convex ; the early chambers spirally 

 arranged, later ones long and becoming annular or nearly so about 

 the periphery; chambers of living forms usually simple but often 

 patially divided by internal septse, visible from the exterior ; aper- 

 ture elongate, at the inner border of the chamber. 



Genus DISCORBIS Lamarck, 1804 (DISCORBINA of Authors) 



Plate 10, fig. I 



Test free or attached, spiral and rotaliform, plano-convex or 

 bicouA^ex, or modified variously in different species ; typically plano- 

 convex with the ventral side flattened and the dorsal convex ; all cham- 



