KEY TO CLASSES AND ORDERS OF ANIMALS g 



6(13) Body with indistinct cuticula, often more or less 

 ameboid. 7 



7(8) Body elongate with undulating membrane. (Pratt, 

 30; Calkins, 244; Minchin, 283.) 



Order Trypanosomatida 



8(7) No undulative membrane present. 9 



9(10) Two or more flagella, one directed forward, the other 

 trailed behind. (Pratt, 29; W. and W., 248.) 



Order Heteromastigida 



10(9) Flagella always directed forward. 11 



11(12) One or two flagella; body usually more or less ameboid. 

 (W. and W., 243; Pratt, 26.) Order Monadida 



12(11) Three or more flagella. (Pratt, 30.) 



Order Polymastigida 



13(6) Body with distinct cuticula. (Pratt, 31; W. and W., 

 251.) Order Euglenida 



14(1) Body usually either yellow or green, often colonial. 15 



15(16) Body with distinct cuticula, and usually solitary. 

 (Pratt, 31; W. and W., 251.) Order Euglenida 



16(15) Body usually with a hyaline, gelatinous or cellulose 

 house, colonial. (Pratt, 34; W. and W., 249.) 



Order Phytoflagellida 



Subclass DINOFLAGELLATA 



1(2) Without furrows, the two flagella free in the water, 

 the transverse with movement the same as though 

 the furrow were present. (Pratt, 39.) Order Adinida 



2(1) With furrows, one transverse, the other longitudinal. 

 (Pratt, 40; W. and W., 269.) Order Diniferida 



