276 



CLASS: MASTIGOPHORA 



may be absent, the organism being capable of amoeboid movements. Some 

 forms develop cup-like loricse in which they live. Numerous individuals 

 may be held together by a gelatinous matrix to form colonies. The order 

 (=Chrysomonadina Stein, 1878) includes Chrysamopba, Ochromonas, Chro- 

 mulina, Pontosphcera, and other genera i^ 



(Fig. 123). ^\V 



2. Order: CRYPTOMONADIDA. 

 Small forms with two flagella and a 

 thick, rigid periplast, which gives them a 

 characteristic ovoid shape. The body is 

 often flattened, while a longitudinal groove 

 is frequently present on one surface. This 

 asymmetry permits of a definite orientation. 

 Chromatophores of varying colour are usu- 

 ally present. Included in the order {= Cryp- 

 tomonadina Stein, 1878) are Cryptomonas, 

 Chilomonas and other genera (Fig. 124). 



Fig. 124. — ^A, Crijj)toriionas ovata; B, Chilomonas 

 Paramecium (x 1,000). (After Doflein, 

 1916.) 



Chr, Chromatophore; B, blepharoplast ; N, nucleus; 

 8, oesophagus; Rh, rhizoplast. 



Fig. 125. — CeraUumJiirudinella : 

 Optical Section (Length 

 100-700 Microns). (From 

 Doflein, 1916, after Lau- 

 terborn.) 



N, Nucleus ; Rf, equatorial groove with 

 flagellum; ^gr, long free flagellum. 



3. Order: DINOFLAGELLATA Butsciili, 1885. 

 These organisms, known also as Peridinians, which are mostly marine 

 forms, have a thick, rigid covering to the body, which is variously shaped. 



