HOW TO KNOW THE FRESH-WATER ALGAE 



9a Cells inclosed in a brown shell (test), variously shaped, (round, 

 oval, or flask-shaped), often with a collar about the aperture through 

 which a single flagellum extends. (The variously shaped cells of 

 this genus frequently are found empty, yellow to dark brown, 

 smooth or decorated.) Fig. 5 TRACHELOMONAS 



Fig. 5a. Trachelomonas granulosa Playf., a 

 short-collared species which has a warty 

 shell; b. Trachelomonas euchlora (Ehr.) 

 Lemm., protoplast within shell, showing eye- 

 spot, chloroplasts, and flagellum. 



There are several hundred species of Tra- 

 chelomonas, each showing a differently 

 shaped shell, or lorica, and each having its 

 own special style of decoration. Usually the 

 loricas are found empty, brown, yellow, or 

 sometimes nearly colorless (determined by 

 the amount of iron present in the shell), intermingled with the mis- 

 cellaneous algae that grow in shallow water or bogs, or among weed 

 beds near the shores of lakes. 



Figure 5 



9b Cells not inclosed in a test 



10 



10a Cells flattened as seen from the side and often twisted; broadly 

 fusiform or nearly round in outline when seen from the front; 

 paramylum in the form of one to several 'doughnut' rings, or 

 discs. Fig. 6 PHACUS 



Fig. 6a. Phacus curvicauda Swir., front 

 or ventral view showing eye-spot, 

 chloroplasts, and 2 ring-shaped para- 

 mylum bodies (food reserve); b, c, 

 Phacus triqueter (Ehr.) Duj. as seen 

 in end view, the triangular shape 

 being produced by the dorsal flange. 



Although some species are spirally 

 twisted and 'top-shaped' most are flat 

 or at most are only slightly saucer- 

 shaped or pancake-like, with a long 

 or short tail-piece. The rings of stor- 

 age material are usually very con- 

 spicuous and so large as 'to fill nearly the entire diameter of the cell. 



10b Cells not flattened, round in cross section; either elongate-fusi- 

 form or oval to round or somewhat pear-shaped in outline; para- 

 mylum bodies different from above 11 



Figure 6 



24 



