496 PROTOZOOLOGY 



and transform into "fertilization cyst." (S). The nucleus in each 

 individual divides twice or occasionally three times and thus formed 

 multinucleate bodies escape from the tests within the cyst envelope 

 where many gametocytes are produced by multiple fissions. Each 

 gametocyte which contains 12 chromosomes divides into two amoe- 

 boid haploid gametes by meiosis. Gametes developed from different 

 parents presumably undergo fusion in pairs and zygotes are pro- 

 duced (4)- Each zygote becomes proloculum in which the nucleus 

 divides twice and when the coiled tubular chamber of test grows to 

 about three-quarters of a whorl, young microspheric individuals 

 escape from the cyst and lead' independent existence (5) . Myers re- 

 ports the development of Patellina corrugata is similar to that of 

 Spirillina, except the amoeboid gametes possess 12 haploid number 

 of chromosomes. 



In Discorbis patelliformis (Fig. 208, B, 1-5), the same investigator 

 noticed no fertilization cyst during the sexual reproduction, but two 

 megalospheric individuals come in contact and flagellate gametes are 

 produced in them. The zygotes develop within the space formed by 

 the dissolution of septa between chambefs and tests; the zygote 

 nucleus divides repeatedly within each zygote and forms about 40 

 nuclei before a test is secreted. In Elphidium crispa (Fig. 208, C, 

 1-5), there is no direct association of megalospheric individuals dur- 

 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. 



In Patellina corrugata and Discorbis vilardeboanus, Calvez (1950) 

 finds that the postzygotic divisions of the nucleus are mitotic and 

 the trophozoite nucleus is diploid, but meiosis occurs in the tropho- 

 zoite just before multiple division. 



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. 472). Taxonomy (Cushman, 1948); 

 ecology (Phleger and Walton, 1950; Phleger and Parker, 1951); dis- 

 tribution (Post, 1951, Ming, 1952). 



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 



