DESCRIPTIVE CATALOGUE OF RECENT FORAMINIFERA. 2<ll 



Test typically bi- or tri-serial, etc. — Continued. 

 Monomorphous — Continued. 



Segments alternating in three rows. 



Aperture as in Textularia Genus Ferneuilina. 



Aperture simple, produced, central Genus Tritaxia. 



Aperture porous Genus Chrysalidina. 



Segments arranged spirally, with three chambers in each convolution. 



Aperture partially covered by a valvular lip Genus Valvulina. 



Dimorphous. 



Early chambers biserial, later ones uniserial and rectilinear: 



Genus Bigenerina. 

 Early chambers small and biserial, later ones broadly arched and uniserial: 



Genus Pavonina, 



Early chambers planospiral, later ones biserial Genus Spiroplecta. 



Early chambers triserial, later ones uniserial and rectilinear: 



Genus Clavulina. 



Early chambers triserial, later ones biserial Genus Gaudryina. 



Test typically spiral; sometimes hi- or tri-serial ; aperture oblique, comma-shaped 



or some modification of that form Subfamily Euumixin.k. 



Monomorphous. 



Spiral, elongate, more or less tapering, often triserial Genus Bulimina. 



Miich elongated, with a tendency to become asymmetrically biserial : 



Genus Virgulina. 



Distinctly biserial, Textularian Genus Bolivina. 



Biserial; aperture an arched or semicircular orifice with a vertical notch on 



the septal face of the last segment Genus Pleurostomella. 



Dimorphous. 



Early segments bulimine or virguline, later ones uniserial .. Genus Bifarina. 

 Test consisting of a double series of alternating segments, more or less coiled upon 



itself Subfamily Cassidulinin.e. 



Folded on its long axis, and coiled more or less completely upon itself: 



Genus Cassidulina. 

 Broad, arched on the dorsal side, slightly coiled Genus Ehrenbergia. 



Family V. Miliolidte. 



Test irregular, asymmetrical: aperture variable Subfamily Ntjbeci^laimn.k. 



Chamber one, inflated, adherent ; aperture on the convex surface : 



Genus Squamulina. 

 Chambers more than one, in linear or very irregularly spiral series: 



Genus Nubecularia. 

 Test coiled on an elongated axis, in a single plane or inequilaterally ; chambers two 



in each convolution Subfamily Milium MX. E. 



Chambers in a single plane, embracing, the last two only visible: 



Genus Biloculina. 



Chambers biloculine but subdivided in the interior Genus Fabularia. 



Chambers in a single plane, all visible on both sides of the shell: 



Genus Spiroloculina. 

 Chambers inequilateral, coiled round the long axis of the shell so that more than 



two (usually three or five) are visible Genus Miliolina. 



Test dimorphous; partly milioline, partly spiral or rectilinear: 



Subfamily HAUERININ.E. 



Early chambers milioline, subsequently in a straight series Genus Articulina. 



Early chambers partly milioline and partly planospiral. subsequently in a straight 



series (Jen us Vertebralina. 



Early chamber an undivided planospiral tube, subsequently with two or more 

 segments in each convolution Genus Ojahthalmidium. 



