ORDER II 



FORAMINIFERA 



39 



Fahularia Defr. (Fig. 35). Like Biloculina, but relatively larger. General 

 aperture cribriform; Chambers not an empty cavity, but filled with porcell- 

 anous or calcareous matter, and perforated by numerous anastomosing canals 

 which are directed parallel with the axis of convolution. Abundant in the 

 Eocene of the Paris basin. 



Vertebralina d'Orb. (Fig. 36). First-formed portion of test consisting of 

 coil-shaped loops, the segments afterwards becoming joined in rectilinear 

 series. Tertiary and Eecent. 



Idalina Schlumb. Last -for med Chamber completely enveloping all pre- 

 ceding ones. Cretaceous. 



Subfamily E. Peneroplinae Brady. 



Test planospiral or cycUcal, and bilaterally symmetrical ; apertures many. 



Peneroplis Montf. (Fig. 37). Test discoidal, complanate, polythalamous ; 

 direction of growth primarily spiral, gradually becoming rectilinear, while 

 rapidly increasing in width. Septa perforated by numerous pores. Tertiary 

 and Recent. 



A 



^^'V^T^r<-:W 



Fio. 37. 



Peneroplis planatun 

 Montfort. Recent ; 

 Mediterranean. 



Fig. 38. 



Orhiculina nummis- 

 7?mWsd'Orbigny. Plio- 

 cene ; Sienna, Italy. 



Fig. 39. 



A, Orbitolites complanata Lam. Eocene (Cal- 

 eaire Grossier); Paris. B, Portion of same en- 

 larged. 



Orhiculina Lam. (Fig. 38). Test discoidal, first-formed portion spiral, 

 afterwards becoming annular ; polythalamous ; septation regulär, Chambers 

 subdivided ; septa and walls of segments perforate. Tertiary and Recent. 



Orbitolites Lam. (Fig. 39). Test discoidal, circular in outline, both surfaces 

 slightly concave in the middle, attaining comparatively large size, and com- 

 posed of segments which are arranged concentrically about a few spirally 

 coiled primordial Chambers. Septa radially disposed, and perforated by 

 symmetrically placed pores. In the more complicated forms the principal 

 segments are invested with a superficial multilocular layer, the Chambers of 

 which are also arranged in concentric rings and communicate with the 

 principal segments by means of pores. An important rock-building genus, 

 ranging from the Lias onward. 0. praecwsor and 0. circumvuha Gümbel are 

 Jurassic, 0. macropora d'Orb. Cretaceous, and 0. complanata Lam. Tertiary 

 species. 



Subfamily F. Alveolininae Br£f9y. 



Test spiral, elongated in the direction of the axis of coiling ; Chambers divided 

 into secondary chamberlets. ^,^- '~ 



Aheolina d'Orb. (Borelis Montf.) (Fig. 40). Test<fusiform, elliptical or 

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



