440 Illinois State Lnhoratory of Natural History. 



EXPLANATION OF PLATE. 



A., anterior pole. 

 r. v., contractile vacviole. 

 chr.. chromatophore. 

 /"., flagellum. 

 »?., matrix. 

 w., nucleus. 

 nrl., nucleolus. 



ABBREVIATIONS. 



p. sh., outer or primary sheath 

 P. posterior pole. 

 p., outer pellicle of protoplasm, 

 pr., knob-shaped mass of protoplasm 

 P!ir., pyrenoid. 

 .s. sh., secondar}' sheath. 

 St., stigma. 



Plate XXXVIIL* 



Fic. 1. F/atyflorina arwJata, face -view of 32-cell co\ouy. X y.")0. 

 Fig. 2. Face view of Ifi-oell colony, x 628. 

 Fig. 3. Edge view of 32-cell colony. X 3;'>0. 

 Fig. 4. Lateral view of one of the marginal cells. X 1400. 

 Fig. 5, a — e. Outline of the posterior ends of several deformed colonies. 

 X 280. 



* Figures drawu by C. A. Kofoid and inked by Miss L. M. Hart. 



