354 BIOLOGY OF THE PROTOZOA 



take into consideration such widely different types of pseiidopodia 

 as the filopodia and myxopodia, and relationship to the many- 

 chambered Foraminifera in other respects seems equally remote. 

 There are some types such as Lieherkilhnia, which approach the 

 foraminiferon plan of structure and their systematic position must 

 remain somewhat of a puzzle, but for the present we shall retain 

 the older plan of grouping them with the testate Amoebsea. Simi- 

 larly it is a question whether shell-less forms with myxopodia should 

 be included as Reticulosa with the Foraminifera under the term 

 Nuda as Rhmnbler does, or be grouped with fresh-water types in 

 the subdivision Proteomyxa. The latter course is followed in the 

 present work and the Foraminifera are limited to the shell-forming 

 types of marine Sarcodina having myxopodia. This method of 

 solving the difficulty has the one advantage of grouping together 

 all of the monothalamous forms of Sarcodina and of strictly limiting 

 the Foraminifera to polythalamous types. It is a matter, frankly, 

 of expediency and does not involve any one of the numerous theories 

 of rhizopod phylogeny. 



The tendency has been toward a simplification of the classification 

 of Foraminifera. Carpenter's division into Perforata and Imper- 

 forata, also adopted by Brady involves the problem of isomorphs 

 and questionable affinities. Lister's classification, in which the 

 group is divided into some thirty-two families, seems unnecessarily 

 cut up. Rhinnbler's system is much more simple and is adopted 

 here. He distributes the ten families recognized as Foraminifera 

 amongst five "Family Groups" which we indicate as orders in the 

 following system. 



Order I. Archi-Monothalamida = Archi-Monothalmidia, 

 Rhumbler. 



Shells primarily of a single chamber yet often with incomplete 

 septa, incompletely dividing the single chamber into many chambers. 

 Family 1. Rhabdamminidae, Rhumbler— Shells gelatinous, pseu- 

 dochitinous or with foreign bodies cemented on a chitinous mem- 

 brane; always one-chambered but of variable (globular, tube-like, 

 asteroid) form. The chamber of the shell may be partially broken 

 up by incomplete septa; pores absent or casual; openings one or 

 many. 



Genera: Myxotheca, Schaudinn; Allogromia, Rhumbler (both 

 salt and fresh water); Dritrlrotuba, Rhumbler; Astrorhiza, 

 Sandahl; Saccammina, M. Sars; Psammosphoera, F. E. 

 Schultze; Rhizaminina, Brady; llyperaminina, Brady; 

 Rhahdammina, M. Sars; Ilaliphysemo, Bowerbk.; Hippo- 

 crepina, Parker. 



