MYCETOZOA. 15 



Fam. 12. Nummulinidae. Test calcareous and finely tubulated ; typically 

 free, polythalamous, and symmetrically spiral. The higher modifications all 

 possessing a supplemental skeleton and a canal system of greater or less 

 complexity. Fusulina Fischer and Schwagerina Holier extinct, palaeozoic, 

 Nonionina d'O., Polystomella Lam., Archcediscus Brady, carboniferous, 

 Amphistegina d'O., Operculina d'O., Heterostegina d'O., Nummulites Lam. 

 mostly extinct (Carboniferous and Eocene), Cycloclypeus Carp., Orbitoides 

 d'O., JEozoon (?) Dawsou. 



Testamoebiformia (Carter. An. and Mag, 1880). Adherent testaceous 

 Rhizopoda with the general form of Amoeba. Systematic position doubtful. 

 Holocladina test calcareous and branched with pustuliferous surface, 

 Cysteodidyina test calcareous, sessile, unbranched, uniformly punctate surface, 

 Ceratestina test chitirious and polythalamous. 



SUB-CLASS II. MYCETOZOA.* 



Gymnomyxa of large size, formed by the fusion of many small 

 amoeba-like forms. Fruit-like cysts or sporophore, and coated spores 

 are always formed. 



The Mycetozoa were formerly regarded as Plants, and under the 

 name Myxomycetes placed amongst the Fungi. After the discovery 

 that the spores do not produce a mycelium, but hatch out as swarm 

 cells, de Bary introduced the name Mycetozoa. They have the form 

 of large masses of a granular protoplasm bounded by a clear proto- 

 plasm the ectoplasm without granules. These masses, which are 

 called plasmodia and may attain a surface extension of several square 

 inches, infest the damp surface and interstices of vegetable substances, 

 such as dead leaves, rotten wood, or even sound wood. They spread 

 out into a network on their substratum, over which they advance 

 with a creeping movement due partly to the formation of pseudopodia 

 at the advancing margin and partly to the flow of the dark granular 

 endoplasm. The flow of this latter is a rhythmic one, being reversed 

 at nearly regular intervals. The endoplasm contains numerous 

 nuclei and vacuoles, and sometimes granules of calcium carbonate. 

 The vacuoles often contract and expel their contents which is either 

 watery or of refuse matter. Occasionally the streaming ceases, the 

 plasmodium breaks up into masses containing ten to twenty nuclei, a 

 superficial membrane is formed round each of these masses, and they 

 enter a resting state : this is the stage of the Sclerotium. The 

 sclerotium can be made to reassume the active condition by the 

 addition of moisture. 



* De Bary, "Die Mycetozoen." 1864. A. Lister, "A Monograph of the 

 Mycetozoa." London, 1894. W. Zopf, "Die Pilzthiere oder Schleimpilze." 

 Encyklopcedie der Naturwissenschaften, 1885. 



