Z'2. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. '/J 



chambers biserial, occasionally tending to become uniserial in the last 

 developed chambers. 



Genus SPIROPLECTA Ehrenberg, 1844 



Plate 4, fig. 8 



Test with the early chambers close-coiled in both the microspheric 

 and megalospheric forms ; later chambers biserial ; wall typically 

 arenaceous. 



Subfamily 2. TEXTULARIINAE 



Test typically biserial, wholly or in part, the early portion in the 

 microspheric form often with a few coiled chambers, followed by 

 the biserial chambers ; later chambers variously modified in the 

 different genera, vmiserial, broadly extended, etc. ; wall either arena- 

 ceous or calcareous and hyaline, perforate ; aperture single, or in 

 a few cases, many present in a single chamber. 



Genus TEXTULARIA Def ranee, 1824 

 Plate 5, fig. I 



Test elongate, tapering, composed of two series of alternating 

 chambers ; wall calcareous in the young, hyaline and perforate, occa- 

 sionally so throughout the test, often with an external coating of 

 siliceous or calcareous sand, or in some species nearly the whole test 

 arenaceous; aperture typically an arched slit at the inner margin of 

 the chamber close to its line of attachment to the preceding chamber; 

 occasionally with the aperture surrounded by a raised lip, or in some 

 species with the aperture circular and terminal. 



Genus TEXTULARIOIDES Cushman, 191 1 



Test attached, consisting of a Textidarla-XA^t series of chambers, 

 arranged in two series, the chambers of one series alternating with 

 those of the other ; wall arenaceous ; aperture an elongated slit in a 

 depression at the base of the inner margin of the chamber. 



Genus BIGENERINA d'Orbigny, 1826 



Plate 4, fig. 9 



Test free, generally elongate, cylindrical or compressed, the early 

 portion textularian, composed of a series of biserially arranged 

 chambers, later chambers arranged in a single line ; wall usually thick, 

 arenaceous, usually coarse but often smoothly finished; aperture in 



