MASTIGOPHOEA 



41 



C. tripos Ehrenberg (Fig. 56). Body triangular with 1 very long 

 and 2 short curved projections; length .29 mm.: Woods Hole; marine; 

 common. 



C. fusus Ehr. Animal very elongate, due to presence of 2 long 

 projections in the same line; length .28 mm.: Woods Hole; marine; 

 common. 



3. GLENODINIUM Stein. Small globular forms with a transverse 



Fig. 56 



Fig. 57 



Fig. 58 



Fig. 56 Ceratium tripos (Calkins). Fig. 57 Glenodinium compressum (Calkins). 

 Fig. 58 Gymnodinium gracile (Calkins). 



groove on anterior half and a short longitudinal one; shell soft and 

 structureless and without markings: 6 species; in fresh and salt water. 



G. compressum Calkins (Fig. 57). Body ovoid, compressed, with 

 deep transverse and longitudinal grooves; hinder end often pointed and 

 this point becomes attached; length .04 mm.: Woods Hole. 



4. GYMNODINIUM Ehrenberg. Body without shell and spherical, 

 sometimes pointed or flattened: 8 species; in fresh and salt water. 



G. gracile Bergh (Fig. 58). Transverse groove in anterior half; 

 longitudinal groove long; color brown; length .06 mm.: Woods Hole; 

 marine. 



FAMILY 2. DINOPHYSIDAE. 



Transverse groove near upper end of body, its edges as well as edge 

 of the longitudinal groove being usually produced .into 

 characteristic ledges. 



1. AMPHIDINITJM Claparede and Lachmann. Body 

 ovoid and flattened; longitudinal groove extending from 

 hinder end to transverse groove near forward end; shell 

 absent; color, brown or green: 2 species; in fresh and 

 salt water. 



A. operculatum Cl. and Lach. (Fig. 59). Length .04 

 mm.: Woods Hole. 



SUBCLASS 3. CYSTOFLAGELLIDIA. 



Marine flagellates of large size with a parenchymatous protoplasm: 

 several genera. 



Fig. 59 



Amphidinium 



operculatum 



(Calkins). 



