140 THE FORAMINIFERA 



There seems good reason to hope that the study of the plan 

 of growth of both forms of the species during the early stages of 

 their life-histories may throw light on the complicated problems 

 of phylogeny. Until these early stages have received fuller 

 attention, and we have arrived at a conclusion as to the relation 

 of the early to the later stages of the multiform tests, efforts at 

 forming a " natural classification " appear to be premature. 



The classification adopted by Brady in his Challenger Monograph 

 is given here, with slight modifications. I have followed Neumayr 

 (30) in placing the Astrorhizidea before the Miliolidea as they 

 appear to be more primitive forms. The Cycloclypeinae are merged 

 with the Nummulitidae for the reasons given above. 



It appears highly probable that the Lituolidea should be dis- 

 tributed (as Biitschli has done) among the calcareous forms which 

 they resemble, but they are here left as arranged by Brady. 



In conclusion I desire to express my thanks to my brother Mr. 

 W. T. Lister, for his assistance in preparing the photographs of 

 the shells of Foraminifera with which this article is illustrated. 

 They were done with one of Zeiss' admirable instruments. 



ORDER 1. Gromiidea. 



Test membranous, chitinous, or siliceous ; smooth or encrusted with 

 foreign bodies ; with one or more pseudopodial apertures. 



FAMILY 1. POLYSTOMATIDAE. Test with one or many openings. 

 Genus Myxotheca, Schaudinn (Fig. 2). Test encrusted, openings many ; 

 marine. Here may be provisionally placed Hyalopus, Schaudinn 

 ( = Gromia dujardinii, M. Sch.). Test smooth, rounded, with one opening 

 (Fig. 15), or branched, and with many ; pseudopodia hyaline, with few or 

 no anastomoses ; multinucleate ; marine. 



FAMILY 2. MONOSTOMATIDAE. Test rounded or flask -shaped, with 

 a single opening. 



(a) Test smooth. Genera Gromia, Duj. Test chitinous, usually 

 flexible, mouth terminal ; freshwater and marine (Fig. 1). Lieberkiihnia, 

 Clap, and L. Test very delicate, ovoid ; moutli sub-terminal. Mikro- 

 gromia, R Hertw. (Cystophrys, Archer) (Fig. 14). Test small, rigid, flask- 

 shaped, bilaterally symmetrical, not filled by the protoplasm ; pseudopodia 

 springing from a short stalk of protoplasm ; individuals often united by 

 their pseudopodia into colonies. Platoum, F. E. Sch. Similar to Mikro- 

 gromia, but test more pointed. Lecythium, H. and L. Similar, but 

 protoplasm filling the test. These four are freshwater genera. 



(&) Test encrusted with foreign bodies. Genera Pseudodifflugia, 

 Schlumb. Eesembles Gromia, but test encrusted ; fresh and brackish 

 water. Diaphoropodon, Archer. Test ovoid, built of loosely-united foreign 

 bodies. Pseudopodia of two kinds : long, extended from the mouth ; and 

 short, hair-like (? true pseudopodia) between the particles of the test. 



(c) Test built of chitinous or siliceous plates. Genera Euglypha, Duj. 

 (Fig. 3). Test elliptical or pear-shaped, with terminal mouth ; built of 



