EXPLANATION OF PLATE 18 



Gonyaulax catenata (Levander) Kofoid 



All figures magnified 1400 diameters 



Fig. 1. Antapical view of hypotheca. showing plates. 



Fig. 2. Apical view of epitheca, showing plates. 



Fig. 3. Two individuals in cdiain. showing cell contents, nucleus and 

 starch grains. 



Fig. 4. Dorsal view of theca, showing surface structure. 



Fig. 5. Ventral view of same. 



Fig. 6. Diagram of epitheca in apical view, with Levander 's (1894) 

 nomenclature. After Levander (1894) text figure 3. 



Fig. 7. Same of hypotheca from above. After Levander (1894) 

 text figure 4. 



ABBREVIATIONS 



l'-4' — apical series of plates. cl. pi. — closing platelet of apex. 



1(1-4(1 — anterior intercalary plates. int. pis. — intermediate plates of 



l"-6"- — precingular series. ventral area. 



]"'-6"' — postcingular series. post. att. po. — posterior attachment 



IP — posterior intercalary plate. pore. 



1"" — antapical plate. post. pi. — posterior plate of ventral 



ant. att. po. — anterior attachment area. 



pore. 

 ant. pi. — anterior plate of ventral 



area. 



Figures drawn by Mrs. Josephine Rigden Michener. 



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