MASTIGOPHORA. 855 



flagella ; monaxial or a little asymmetrical ; sometimes extremely contractile ; a 

 cuticle ; colourless or green ; an oral aperture at or surrounding the base of the 

 flagellum ; an oesophagus with a contractile vacuole close to it, often provided with 

 a reservoir; includes seven families Coelomonadina, e.g. Chromulina ; Eugle- 

 nina; Chloropeltina, e.g. Phacus ; Menoidina ; Paranemina ; Petalomonadina ; 

 Astasiina. 



3. Heteromastigoda : of variable size and colourless ; two flagella at least, 

 one smaller and directed forwards, the other large and trailing backwards ; an oral 

 spot and in large species a distinct mouth and pharynx ; holozoic ; includes two 

 families Bodonina, e. g. JBodo, Dallingeria ; Anisonemina. 



4. Isomastigoda : of small or medium size ; monaxial, rarely bilateral or 

 asymmetrical ; anterior end with two, four, rarely five similar flagella, arising as a 

 rule near one another ; includes ten families Amphimonadina ; Spongomonadina, 

 Spongomonas, CZadomonas, Rhipidodendron ; Chrysomonadina, e. g. Synura, Syn- 

 crypta ; Chlamydomonadina, e. g. Polytoma, Chlamydomonas, Haematococcus ; Volvo- 

 cina Gonium, Stephanosphaera, Pandorina, Eudorina, Volvox 1 ; Tetramitina ; 

 PoZymastigina ; Trepomonadina ; Cryptomonadina, e. g. Chilomonas, Cryptomonas ; 

 Lophomonadina. 



II. Choanoflagellata : a single flagellum surrounded by a protoplasmic collar : 

 includes two orders. 



1. Phalansterina s. Gelatinigera : collar short, narrow, constant in shape; 

 a gelatinous envelope to each individual or to every two individuals; colonial; 

 colony disc-like, or erect and dichotomously branched ; Phalansterium. 



2. Craspedomanadina : collar large, funnel-shaped, of changeable shape ; 

 solitary or colonial ; divisible into Codonosiginae, e. g. Monosiga, Codosiga, Protero- 

 spongia^ and Salpingoerina with a delicate test of variable shape, Salpingoeca, 

 Polyoeca. 



III. Dinoflagellata : two flagella at least, one parallel to the long axis of the 

 body, the other transverse to it : includes two orders. 



1. Adinida : two flagella at anterior pole; a bivalved envelope pierced by 

 pores ; Exuviaella, Prorocentrum. 



2. Dinifera : one flagellum as a rule turned backwards ; one or more trans- 

 verse flagella lodged in one or more transverse furrows ; (i) Peridinidae, with a single 

 transverse furrow at or near the middle of the body ; sometimes naked ; e. g. Peridi- 

 nium, Ceratium, &c. ; (ii) Dinophysidae, transverse furrow single, more or less 

 anterior ; a bivalved envelope ; e. g. Dinophysis^ Amphidinium ; (iii) Polydinidae, 

 several transverse furrows ; naked ; Polykrikos. 



IV. Cystoflagellata : protoplasm reticulate, a single flagellum ; marine ; Nocti- 

 luca, Leptodiscus. 



(i) Flagellata. Butschli, Protozoa, Bronn's Klass. u. Ordn. des Thierreichs, i. 

 pp. 620-876 ; Kent, Manual of Infusoria, i. 1880-81, pp. 216-322, 366-96, 401-38 ; 



1 The Chrysomonadina, Chlamydomonadina, and Volvocina are holophytic, and provided with 

 chromatophores. Botanists usually consider them as Algae, and Butschli unites them under the 

 common designation of Phytomastigoda, 



