REPORT ON THE FORAMINIFERA. 
75 
finely tubulated. Septa single or rarely double ; no true interseptal canals. Aperture a 
single elongated slit, or a row of small rounded pores, at the inner edge of the final 
segment. 
Test fusiform or subglobular; chambers entire, or only 
subdivided by the infolding of the septal wall ; 
aperture an elongated central fissure, . . Fusulina, Fischer. 
(Sub-genera — Hemi fusulina, Fusulinella, Moller.) 
Test subglobular, elongated, or subcylindrical, seldom 
fusiform; chambers subdivided by true secondary 
septa ; aperture either a simple central fissure or a 
row of rounded pores, .... Schwagerina, Moller. 
Sub-family 2. PolystomellinSB, — test bilaterally symmetrical ; nautiloid. Lower 
forms without supplemental skeleton or interseptal canals ; higher types with canals 
opening at regular intervals along the external septal depressions. 
Supplemental skeleton either absent or rudimentary, and 
confined to the umbilical region ; no external septal 
pores or bridges. Aperture a simple curved slit, . Nonionina, d’Orbigny. 
Supplemental skeleton, septal bridges, and canal-system 
more or less fully developed ; canals opening exter- 
nally at the umbilicus and by a single or double row 
of pores along the sutures. Aperture a V-shaped line 
of perforations at the base of the septal face, . Polystomella, Lamarck. 
(Sub-genus — Fanjasina, d’Orbigny. ) 
Sub-family 3. NummulitinSB, — test lenticular or complanate ; lower forms with 
thickened and finely tubulated shell-wall, but no intermediate skeleton ; higher forms 
with interseptal skeleton and complex canal system. 
Test lenticular ; consisting of a non-septate tube coiled 
upon itself in constantly varying direction, embedded 
in a thick mass of finely tubulated shell-substance. 
No supplemental skeleton nor canal system, . Archcediscus, Brady. 
Test spiral, lenticular, inequilateral ; chambers equitant, 
the alar prolongations on one side simple, on the 
other divided by deep constrictions so as to form 
supplementary lobes. Shell- wall thickened near the 
umbilicus and finely tubulated, but presenting no 
true canal system, ..... Amphistegina, d’Orbigny. 
