ORDER I FORAMINIFERA 25 
Family 1. Nubecularidae. Brady. 
Test comparatively large-sized, usually attached, extremely irregular in contour, 
with one or with several general apertures. Triassic to Recent. 
‘The recent genus Nubecularia, Dir., belonging to this family occurs fossil 
in all formations from the Triassic onward, and is particularly abundant in 
the Miocene (Sarmatian stage) of Bessarabia, Russia. 
Family 2. Peneroplidae. Schwager. 
Test plano-spiral or cyclical, bilaterally symmetrical, usually polythalamous, more 
rarely monothalamous. ‘Triassic to Recent. 
Cornuspira, Schultze (Fig. 19). Test composed of numerous plano-spiral 
convolutions; oral aperture simple, terminal; monothalamous. Lias to 
Recent. 
Peneroplis, Montf. (Fig. 20). Test discoidal, complanate, polythalamous ; 
direction of growth primarily spiral, gradually becoming rectilinear, while 

Cornuspira poly- Fic. 22. 
gyra, Reuss. Peneroplis planatus, Orbiculina nummis A, Orbitolites complanatu, Lam. Eocene 
Oligocene: Hun- Montfort. Recent; malis, @Orb. Plio- (Caleaire Grossier); Paris. B, Portion of 
gary. Mediterranean. cene ; Sienna, Italy. same enlarged. 
rapidly increasing in breadth. Septa perforated by numerous foramina. 
Tertiary to Recent. 
Orbiculina, Lam. (Fig. 21). Test discoidal; segments spiral at commence- 
ment, later becoming annular; polythalamous, septation regular, chambers 
subdivided ; septa and walls of segments perforate. Tertiary to Recent. 
Orbitolites, \Lam. (Fig. 22). Test discoidal, circular in contour, both sides 
slightly concave in the centre, of comparatively large dimensions, and com- 
posed of segments which 
are disposed concentrically 
about a few spirally wound 
primordial chambers. 
Polythalamous; septa 
radially disposed, and per- 
forated by symmetrically Alveolina Bosei, VOrb. Eocene (Caleaire Grossier); Paris. 4A, Frontal 
distributed foramina. In aspect. B, Test laid open so as to show conformation of interior ; 
the more complicated considerably enlarged. 
forms the principal segments are covered over on both sides by a thin, super- 
ficial, multilocular layer, the chambers of which are likewise arranged in con- 
centric rings, and communicate with the principal chambers by means of pores. 
Lias (0. praecursor and O. cireumvulva, Giimb.), Cretaceous (0. macropora, 

Fic. 23. 
