STUDIES nsr rORAMmrFERA 



13 



and elongate, short and spatulate, or of various 

 other shapes, e. g., Globoroialia. 

 Lateral apertural flanges: Similar to the aper- 

 tnral lip of trochospiral forms, but foimd on both 

 sides of the commonly elevated peripheral aperture 

 in Hantkenina, Clavigerinella, and related genera. 

 Umbilical teeth: A triangular modification of the 

 apertural lip, those of successive chambers in forms 

 with an umbilical aperture giving a characteristic 

 serrate border to the umbUicus as in Globoquadrina. 

 Chamber flanges: Broad folds developed along the 

 basal margins of chambers which tend to obscure 

 the sutures and thereby to cover the sutural and 

 umbilical apertures as in Sphaeroidinella. 

 Tegilla (singular, tegillum ; derivation : Latin dimin- 

 utive of tegulum, roof, cover): This new term is 

 proposed for the lunbilical coverings of the Globo- 

 truncanidae {Globotruncana, Rugoglobigerina) which 

 are extensions from the chambers, similar to a 

 highly developed apertural lip, but which extend 

 across the umbilicus, completely cover the primary 

 aperture, and attach at their farther margin or at 

 the tegilla of earlier chambers. Generally delicate 

 and with thinner walls than the true chambers they 

 may be broken out of the umbilical area and are 

 comonly found only as ragged fragments. With 

 great care in preparation of well-preserved material 

 they may also be found in all species of these genera. 

 They may have smaller openings along their mar- 

 gins, or be pierced centrally, these openings com- 

 municating beneath the tegilla with the primary 

 umbihcal apertures and the umbilical area. 

 Bulla (plural, bullae; derivation: Latin, blister): 

 This term is here defined to include the accessory 

 structiu"es found in many planktonic Forminif era of 

 the family Orbulinidae, which in general are not 

 closely related to the primary chambers, but are 

 instead related only to the aperture. They may 

 partially or completely cover the primary or sec- 

 ondary apertures, and may have one or more 

 accessory apertures at their margins. 

 Umbilical bulla. A bulla covering the umbilicus 



and the apertures leading into it, as in Cata- 



psydrax. 

 Sutural bullae. Bullae covering the secondary 



sutural apertures and only sutural in position, as 



in Globigerinatheka. 

 UmbUical-sutural bulla. A bulla covering both 



the umbilicus and the apertures leading into it 



and extending along the sutures as well, as in 



Globigerinita. 

 Areal bullae. Bullae covering the multiple areal 



apertures as in Globigerinatella. 



Apertural Openings in Test 



These include the relatively large openings commonly 

 termed apertures, which in general are characteristic 



for each genus, both in position and shape. The fine 

 pores in the wall for the extrusion of pseudopodia are 

 not considered here (text-fig. 5). 



Primary Aperture 



This is the main aperture opening from the final 

 chamber of the test. In the families imder considera- 

 tion here, all primary apertures are interiomarginal, 

 that is "at the base of the final chamber," but may vary 

 in position as follows: 



Umbilical: Opening from the final chamber directly 

 into the umbilicus, on the umbilical side of tro- 

 chospiral forms. Those of earlier chambers may 

 also remain open, as in Globigerina. 



Extraumbilical-umbilical: Extending from the 

 umbilicus along the forward margin of the final 

 chamber toward the periphery, and thus reaching a 

 point outside the umbilicus, or extraumbilical as in 

 Globoroialia. 



Equatorial: This is characteristic of the planispiral 

 forms, and is a symmetrical interiomarginal aper- 

 ture in the final chamber, just above the peripheral 

 margin of the previous whorl. It may be extremely 

 high as in Clavigerinella, triradial as in Hantkenina, 

 or a low arch as in Hastigerinoides. 



Spiro-umbilical: An interiomarginal aperture ex- 

 tending from the umbilicus to the periphery and 

 finally on to the spiral side; the most extensive 

 aperture found in trochospiral forms, e.g., Hasti- 

 gerinella. 



Secondary Apertures 



These include smaller openings which are developed 

 in addition to the primary aperture, but in specialized 

 forms may completely replace the primary aperture. 



Relict apertures: In the Planomalininae the um- 

 bilical portions of the equatorial aperture may 

 not be covered by succeeding chambers, but re- 

 main open as short radial sUts aroimd the umbili- 

 cus. Even when they are secondarily closed, the 

 elevated apertural lips or flanges remain visible 

 around the umbilicus, as in Planomalina and 

 Hastigerinoides. 

 Supplementary apertures: These may occur in 

 addition to the primary aperture and thus are 

 independent of it. In some cases they may 

 completely replace the primary aperture. 

 Areal. Supplementary multiple areal apertures 

 are developed in Cribrohantkenina. Specimens 

 may be found in which both the primary equa- 

 torial aperture and the supplementary areal 

 apertures occur, showing the latter to be of 

 secondary rank. 

 Sutural. Sutural supplementary apertm-es are in 

 general relatively small. They may be single, 

 or one per suture, as in Rotalipora, or multiple, 



