Phylum Protoplasta [ 195 



capsule membrane and by the absence of skeletal spicules extending across the central 

 capsule or meeting in its middle. Except during reproduction, each central capsule 

 contains a single nucleus, but the cells of many examples are coenocytic, containing 

 several or many central capsules. 



Brandt (1885, 1905) observed reproduction particularly as it occurs by the produc- 

 tion of swimming cells by some of the coenocytic forms. The nucleus divides to pro- 

 duce very many, and the intracapsular cytoplasm divides to produce uninucleate 

 flagellate cells. In Collosphaera, all the nuclei are included in these cells. The cells 

 are of two sizes, produced by different individuals, and are supposed to be gametes. In 

 Sphaerozoum and its allies, some of the nuclei degenerate instead of being included 

 in the swimming cells, of which two sizes are produced by single individuals. It ap- 

 pears that the swimming cells have characteristically two unequal flagella, though 

 many are found to have only one, and some produce a third appendage by which 

 they can attach themselves. 



Haeckel listed thirty-two families in his legion Spumellaria. Other authors recog- 

 nize about a dozen, including the following. 



Family ThalassicoUida Haeckel (1882). Thalassicollen J. Miiller (1859). Family 

 Collida Haeckel (1862); there is no corresponding generic name. Order Collida 

 Haeckel (1887). Globular forms with a single central capsule, skeleton none or of 

 numerous small spicules. Thalassicolla, Physematium, Lampoxanthium, etc. 



Family Sphaerozoida Haeckel (1882). Family Collozoida Haeckel op. cit. Family 

 Sphaeroidina Haeckel (1862); there is no corresponding generic name. Coenocytic, 

 each cell with several nuclei in separate central capsules; skeleton none or of numer- 

 ous small spicules. Sphaerozoum, the cells globular, to 1 mm. in diameter; Raphido- 

 zoum, the cells elongate. 



Family CoIIosphaerida Haeckel (1862). Coenocytic, the spherical cell to 1 mm. in 

 diameter, with several central capsules, each with an individual lattice-like skeleton. 

 Collosphaera. 



Family Haliommatina Ehrenberg 1847. Families Ethmosphaerida, Ommatida, 

 and Cladococcida Haeckel ( 1862) . Family Sphaerida Haeckel ( 1882) . Order Sphaer- 

 oidea, with six families, Haeckel '(1887). Globular, with small numbers of radiating 

 main spicules, the main spicules bearing tangential branches which form a globular 

 network of definite pattern, or, often, two or more concentric networks. Haliomma, 

 Actinomma, Hexacontium, Cladococcus, and many other genera. 



Further families are of the character of the Haliommatina, but with the spherical 

 symmetry modified by abbreviation or elongation of one or more axes: 



Family Spongurida Haeckel (1862). Order Prunoidea, with seven families, 

 Haeckel (1887). Having one axis elongate. Spongurus, Pipetta, etc. 



Family Lithocyclidina Ehrenberg 1847. Family Discida Haeckel (1862). Order 

 Discoidea, with six families, Haeckel ( 1887) . Having one axis shorter than the others. 

 Lithocyclia, Staurocyclia, Heliodiscus, etc. 



Family Larcarida Haeckel (1887). Order Larcoidea, with this and seven other 

 families, Haeckel (1887). The skeleton with three unequal axes, or spiral. Cenolar- 

 cus, etc. 



Order 3. Acantharia Haeckel in Jenaische Zeitschr. 15: 465 (1882). 

 Order Actipyleen Hertwig Org. Radiolar. 133 (1879). 



Legion Acantharia or Actipylea, orders Acanthometra and Acanthophracta, and 

 seven suborders, Haeckel in Rept. Voy. Challenger Zool. vol. 18 (1887). 



