FORAMINIFERA 



497 



Genus Rhabdammina Sars (Fig. 209, a) 



Test without a central chamber, elongate, open at both ends; fossil 

 and recent Family 2 Rhizamminidae 



Genus Rhizammina Brady (Fig. 209, b) 



Test a chamber or rarely series of similar chambers loosely attached, 



with normally a single opening; fossil and recent 



Family 3 Saccamminidae 



Genus Saccammina Sars (Fig. 209, c) 



Test 2-chambered, a proloculum and long undivided tubular second 

 chamber 



Fig. 209. a, Rhabdammina abyssorum, X5 (Ktihn); b, Rhizammina 

 algaeformis, fragment of, Xl4 (Cushman); c, Saccammina sphaerica, 

 X8 (Rhumbler); d, Hyperammina subnodosa, x4 (Brady); e, Ammo- 

 discus incertus, X20 (Kiihn); f, Silicina limitata, Xl3 (Cushman); 

 g, Reophax nodulosus, X3 (Brady). 



Test with the second chamber, simple or branching, not coiled; 

 mostly recent and also fossil Family 4 Hyperamminidae 



Genus Hyperammina Brady (Fig. 209, d) 



Test with the second chamber usually coiled at least in young 

 Test of arenaceous material with much cement, usually yellowish 

 or reddish brown; fossil and recent . Family 5 Ammodiscidae 



Genus Ammodiscus Reuss (Fig. 209, e) 



Test of siliceous material, second chamber partially divided; 

 fossils only Family 6 Silicinidae 



Genus Silicina Bornemann (Fig. 209, f) 



Test typically many-chambered 



Test with all chambers in a rectilinear series; fossil and recent 



Family 7 Reophacidae 



