34 



PROTOZOA RHIZOPODA 



CLASS I 



cesses. The ramifications of these lateral processes (Filet cloisonnaire) may be 

 readily seen on fracturing a portion of the test, and are a 

 valuable aid in the determination of species. The oldest 

 Nummulites (N. pristinus, Brady) occur very sparsely in the 

 Carboniferous Limestone and Upper Jurassic, but are dis- 

 tinguished from the typical later forms by the absence of 

 an interior canal-system in the marginal cord. The typical 

 Nummulites which are so characteristic of the Eocene (Num- 

 mulitic limestone) in Europe, North Africa, Asia, and Central 

 America, often build up massive formations. The largest 



Eocene?pyrenees? w ' species (N. Giztliensis, Ehrbg., N. orbiculatus, Schafh.) attain 

 a diameter of 60 mm. ; the smallest species does not exceed 



2 mm. ; recent representatives comparatively scarce. 



Polystomella, d'Orb. (Fig. 44) ; Nonionina, d'Orb. ; Cydodypeus, Carp. 



Tertiary and Recent. 



FIG. 41. 

 Nummulites (Assi- 





12 



FIG. 42. 



A, Nummulites Gizehensis, Ehrbg. Eocene ; Libyan Desert. Natural size. A 3, Specimen with eroded peri- 

 pheral portion, showing arrangement of septa. B* 2 , Nummulites laevigatus, Lam. Caleaire Grossier ; Paris. 

 Natural size. B*, Portion of same enlarged. G' 12 , Nummulites Ramondi, Defr. Eocene (Nummulitic lime- 

 stone) ; Pyrenees. Natural size. C$, Enlarged section. 



\/ Orbitoides, d'Orb. (Hymenocydus, Bronn ; Lycophrys, Montf.), (Fig. 45). Test 

 discoidal, with circular or stellate contour, of ten. bent, exterior smooth or. with 



FIG. 43. 



A, Nummulitic limestone with horizontal sections of 

 N. distans, Pusch. Peyrehorade, in the Pyrenees. , 

 Nummulitic limestone showing sections of N. 

 Defr. Zakophane in the Carpathians. 



N. Lucasanus, 



FIG. 44. 



f Polystomella crispa, Lam. 

 Pliocene ; Sienna, Italy. 

 (Highly magnified.) 



radial striae, and composed of numerous concentric annuli disposed about a 



