PROTOZOA RHIZOPODA 



CLASS I 



d'Orb.), Tertiary (0. complanata, Lam.), and Recent. An important rock- 

 building genus. 



Alveolina, Bosc. (Borelis, Montf.), (Fig. 23). Test fusiform, elliptical, or 

 spherical, usually elongated in the axis of convolution, and composed of 

 spirally wound segments which completely envelop one another. Each seg- 

 ment is partitioned off into long, narrow chambers by septa arranged at right 

 angles to the axis, and these are subdivided into chamberlets by a second set 

 of septa running transversely to the first set. Each of the secondary 

 chamberlets communicates with the adjacent primary chamber by means of a 

 single round aperture. In certain recent species the secondary chamberlets 

 are also subdivided. The genus begins in the Cenomanian, continues in 

 extraordinary profusion, and becomes a most important rock-builder in the 

 Eocene (Calcaire Grossier of the Paris basin, Alveolina limestone of Istria, 

 Dalmatia, Greece, and the Libyan Desert). 



Family 3. Miliolidae. Carpenter. 



Test either entirely composed of coil-like segments, or convoluted only at commence- 

 ment. Primordial chamber dimorphous. Triassic to Recent. 



Miliola, Lam. (Figs. 24, 25). Segments disposed in ' coil- shaped loops 

 about a few spirally wound primordial chambers. Each loop is constricted at 



FIG. 24. 



A, Biloculina inornata, d'Orb. From the Miocene Tegel ; Baden, near Vienna. />', TrilocuUna gibba, d'Orb. 

 Oligocene sand from Astrupp. C, Spiroloculina Badensii, d'Orb. Miocene Tegel ; Baden, near Vienna. D, Quin- 

 queloculina saxorum, d'Orb. Eocene (Calcaire Grossier) ; Grignon, near Paris. 



the extremities so as to form a septum of its own walls. Terminal pseudo- 

 podial aperture either curving in the form of a crescent about a tooth-like pro- 



jection, or branching 

 dendritically (Lacazina). 

 Forms having all the seg- 

 ments disposed in a single 

 plane, and all externally 

 visible, are grouped to- 

 gether in the sub -genus 

 Spiroloculina, d'Orb. ; with 

 all the segments completely 



A, Longitudinal section of 

 Biloculina inornata, d'Orb. 

 (enlarged). B, Transverse 

 section of Quinqucloculina 

 saxornm, d'Orb. (enlarged). 



FIG. 26. 



FIG. 27. 



I''<ilniJuria dis- 

 colithes, Defr. 

 Eocene (Calcaire 

 Grossier); Paris. 



enveloping 



cronata, 

 Recent ; 

 terranean 



one another, 



,,Q ^ -tvwi/i/u/t/frfiw/, VA Orb.j segments 

 M-<ii- disposed in three or in five 

 different planes, TrilocuUna 

 and Quinqueloculina, d'Orb. The great variety and extraordinary profusion of 

 this genus combine to make it one of the most important of the rock-building 

 Foraminifera. Massive beds of Eocene limestone (Paris basin, Pyrenees) are 



