DESCRIPTIVE CATALOGUE OF RECENT FORAMINIFERA. 261 



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

 Monomorphous Continued. 



Segments alternating in three rows. 



Aperture as in Textularia Genus Yerneuilina. 



Aperture simple, produced, central ! Genus Tritaxia. 



Aperture porous Genus Chrysalidina. 



Segments arranged spirally, with throe 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 uuiserial: 



Genus Pavonlna. 



Early chambers planospiral, later ones biserial Genus Spiroplecta. 



Early chambers triserial, later ones uniserial and rectilinear: 



Genus Clarulina. 



Early chambers triserial, later ones biserial Genus Gaudryina. 



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



or some modification of that form Subfamily BULIMININ^E. 



Monomorphous. 



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



Much elongated, with a tendency to become asymmetrically biserial: 



Genus Virgulina. 



Distinctly biserial, Textularian Genus Bolimna. 



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



the septal face of the last segment Genus Pleurostomclla. 



Dimorphous. 



Early segments bulimine or virguline, later ones uui serial.. Genus Bifarina. 

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



itself Subfamily CASSIDULININ.'K. 



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. MILIOLID.E. 



Test irregular, asymmetrical : aperture variable Subfamily NUBECULARIN.E. 



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



Genus Squamulina. 

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



Genus Nnlecnlaria. 

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



in each convolution Subfamily MILIOLJNIN^E. 



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



Genus HilocuUna. 



Chambers biloculine but subdivided in the interior Genus Fdbularia. 



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 HAUERINITSLE. 



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



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



series Genus Veriebralina. 



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

 segments in each convolution Genus Ophthalmidium. 



