50 



Fresh-water Biology 



3— Pseudopods flowing RHIZOPODA 



— Pseudopods ray like HELIOZOA 



4 — Animals with cilia CILIATA. (See page 54) 



— Animals with one or two, rarely more, long flagella. AIASTIGOPHORA. (See 

 page 55.) 



C.B. 



Fig. 2. Transverse section of the frustule of a 

 Navicula. (From Van Heurck, after West.) CB 

 and CB', the two connecting-bands forming the 

 girdle; R, raphe; CX^, central noflule; C, costa of 

 valve. 



Plate 20. Diatoms 



Achnanthidium, 39, 40 

 Amphora, 41 

 Asterionella. 37 

 Campylodiscus, 31, 32 

 Cocconeis, 17 

 Cyclotella, 9, 10 

 Cymbella. 33 

 Diatoma, 12, 13, 14 

 Epithemia, 35 

 Eunotia, 6, 7 

 Fragilaria, 15 

 Frustulia, 18 

 Gomphonema, 29, 30 

 Gyrosigma, 23 

 Melosira, 1, 2, 3, 4 

 Meridion, 11 

 Navicula, 24, 25, 26, 27 

 Nitzchia, 19, 20 

 Pinnularia, 34 

 Stauroneis, 16 

 Stephanodiscus, 5,^8 

 SurieUa, 21, 22 

 Synedra. 38 

 Tabellaria, 28, 36 



