5 8 I KOTOZOA chap. 



faeces of several mammals. The best monograph of this group 

 is that of Penard. 1 



2. FORAMINIFERA 2 



Sarcodina with no central capsule or distinction of ectosarc ; 

 the pseudopodia fine, branching freely, and fusing where they meet 

 to form protoplasmic networks, or the outermost in the pelagic 

 forms radiating, but loithout a central or axial filament : some- 

 times dimorphic, reproducing by fission and by rhizopod or 

 flagellate germs in the few cases thoroughly investigated : all marine 

 {with the exception of some of the Allogromidiaceae), and usually 

 provided with a test of carbonate of lime (" vitreous " ccdcite, or 

 " porcellanous" aragonitef), or of cemented particles of sand 

 (" arenaceous ") ; test -wall continuous, or with the walls perforated 

 by minute pores or interstices for the protrusion of pseudopodia. 



The classification of Carpenter (into Vitreous or Perforate, 

 Porcellanous or Imperforate, and Arenaceous), according to the 

 structure of the shell, had proved too artificial to be used by 

 Brady in the great Monograph of the Foraminifera collected by the 

 "Challenger" Expedition, 3 and has been modified by him and others 

 since then. We reproduce Lister's account of Brady's classifica- 

 tion. 4 We must, however, warn the tyro that its characterisations 

 are not definitions (a feature of all other recent systems), for rigid 

 definitions are impossible : here as in the case, for instance, of 

 many Natural Orders of Plants, transitional forms making the 

 establishment of absolute boundaries out of the question. In 

 the following classification we do not think it, therefore, necessary 

 to complete the characterisations by noting the extremes of 

 variation within the orders : 



1. Allogromidiaceae : simple forms, often fresh-water and similar to Ehizo- 

 poda ; test 0, or chitinous, gelatinous, or formed of cemented particles, whether 

 secreted platelets or ingested granules. Biomyxa, Leidy = Gymnophrys, Cienk. ; 



1 Faune Bhizopodique du Bassin du Leman, 1902. See also Cash, The British 

 Freshwater Bhizopoda and Heliozoa, vol. i., Ray Society, 1905. 



" 2 Chapman, The Foraminifera, London, 1902; Lister, "Foraminifera" in Lan- 

 kester's Treatise on Zoology, pt. i. fasc. 2, 1903. 



3 Challenger Reports (Zool.), vol. ix. 1884. 



4 In Lankester's Treat. Zool. pt. i. fasc. 1. For other classifications see Eimer 

 and Fickert in Z. wiss. Zool. lxv. 1899 ; Rhumbler in Lang's Protozoa, 1901 ; 

 and for a full synopsis of genera and species, " Systematische Zusammenstellung 

 der recenten Reticulosae " (pt. i. only), in Arch. Prot. iii. 1903-4, p. 181. 



