ORDER II FORAMINIFERA 35 



which canals are not present; solid wedge-shaped deposit of intermediate 



Fig. 27. 



Nummulites cfr. lucctsamts Dfr. Eocene ; Kressenberg, Upper Uavaria. Several times enlarged. 

 a, Marginal cord with canal-system ; ?^ Septal plane with interseptal canal-system ; c, Interior of Chamber ; 

 d, Finely perforate periphery ; e, Small pillars of intermediate skeleton. 



skeleton near the umbilicus. On one side the volutions completely enclose 



one another as far as the centre, on the other they overlap 



only partially by meaiis of alar proloiigations extending in- 



wards. Chambers communicate with each other by means 



of a slit along the basis. Miocene to Recent. Particularly 



abundant in Miocene. 



Operculina d'Orb. (Fig. 25). Test discoidal, complanate, 

 composed of three to six rapidly expanding spiral whorls, 

 which are polythalamous and non-involute. Septa and 

 marginal cord traversed by a direct canal-system, which gives 

 off numerous branches. Cretaceous to Recent. Particularly 

 abundant in Eocene. 



Heterostegina d'Orb. (Fig. 26). Like Ojperculina, but with Chambers sub- 

 divided by secondary septa into chamberlets. Tertiary and Recent. 



Fig; 28; 



Nummulites (Assi- 

 lina) exponens 



Eocene 



Sow. 

 Pyrenees. 



C 3 C' 1 2 Fig. 29. 



A 1 ••i, Nummulites (jizchensis Ehrbg. Eocene ; Libyan Desert. Natural size. A -^ Specimen with eroded peri- 

 pheral i)ortion, showing arrangement of septa. B^^, Nximmulites laevigatus Lam. Calcaire Grossier ; Paris. 

 Natural size. B'i, Portion of same enlarged. C^^, Nummulites ramondl Defr. Eocene (Nunimulitic lime- 

 stone) ; Pyrenees. Natural size. C 3, Enlarged section. 



Nummulites Lam. (Phacites Blumenb. ; Lenticulites Lam.) (Figs. 27-29). Test 



