398 PROTOZOOLOGY 



ing sexual reproduction. The flagellated gametes produced in each, 

 are set free in the water and the fusion of the gametes depends en- 

 tirely upon the chance meeting. 



More than 300 genera of extinct and living Foraminifera are now 

 known. Cushman distinguished 45 families. The present work fol- 

 lows Cushman in recognizing and differentiating 44 families, and 

 lists one genus as an example for each, but places Gromia and allied 

 genera in the order Testacea (p. 374). 



Test entirely or in part arenaceous 



Test single-chambered or rarely an irregular group of similar chambers 

 loosely attached 

 Test with a central chamber, 2 or more arms; fossil and recent. . . . 

 Family 1 Astrorhizidae 



Genus Rhabdammina Sars (Fig. 185, a) 



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

 and recent Family 2 Rhizamminidae 



Genus Rhizammina Brady (Fig. 185, 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. 185, c) 



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

 chamber 

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

 mostly recent and also fossil Family 4 Hyperamminidae 



Genus Hyperammina Brady (Fig. 185, 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. 185, e) 



Test of siliceous material, second chamber partially divided; 

 fossils only Family 6 Silicinidae 



Genus Silicina Bornemann (Fig. 185, /) 



Test typically many-chambered 



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



Family 7 Reophacidae 



Genus Reophax Montfort (Fig. 185, g) 



Test planispirally coiled at least in young 



Axis of coil, short; many uncoiled forms; fossil and recent 



Family 8 Lituolidae 



