FAMILY 8. LITUOLIDAE 105 



the higher groups of the arenaceous foraminifera took their 

 origin. The simplest of them are among the oldest known of 

 the foraminifera. Most of the genera of this family are now 

 known from the Palaeozoic. 



FAMILY 8. LITUOLIDAE 



Test free, planispiral at least in the young, later portion in 

 some genera uncoiled, divided into chambers, either simple or 

 labyrinthic ; wall arenaceous with varying proportions of cement 

 in different genera and species, usually with a yellowish- or 

 reddish-brown cement, the last-formed chamber in the adult 

 often white; aperture simple or compound. 



KEY TO THE GENERA 



I. Test of simple chambers, not labyrinthic. 



A. Close coiled throughout. 



1. Aperture simple. 



a. Not at all involute Trochamininoides. 



b. More or less involute. 



(1). Usually coarsely arenaceous, without an exterior 



layer Haplophragmoides. 



(2). Usually finely arenaceous, with an exterior layer. 



Endothyra. 



2. Aperture, a series of openings at the base of the apertural 



face Cribrostomoides. 



B. Later portion uncoiled. 



1. Aperture simple. 



a. Chambers rounded or flattened, but not greatly expanded. 



Ammobaculites. 



b. Chambers very broad in the adult, frondicularian. 



Flabellammina. 



2. Aperture multiple Haplophragmium. 



II. Test with labyrinthic chambers. 



A. Close coiled throughout. 



1. Only slightly compressed Cyclammina. 



2. Very strongly compressed, complanate Choffatella. 



3. Very strongly compressed, many small chamberlets. 



Dictyopsella. 



B. Later portion uncoiled. 



1. Irregular in shape, interior with partitions Lituola. 



2. Regular in shape, interior simply labyrinthic. 



Psetidocyclammina. 



