Kofoid. — Mutations in Ceratium. 



PLATE 4. 



Fig. 4. Mutating chain of Ceratium, dorsal view. The anterior cell is C. osten- 



feldi (1) ; the posterior, C. calif orniense. X 540. 

 Fig. 5. Tip of antapical of anterior cell of the chain shown in fig. 4. X 467. 

 Fig. 6. Mutating chain of Ceratium. Anterior member is C. californiense, and 



posterior one resembles C. ehrenbergi (1), dorsal view. X 450. Station 



4740. 

 Fig. 7. Normal chain of C. vultur, twisted at the fifth cell from the rear, showing 



ventral view anteriorly, and dorsal, posteriorly. X 100. Station 4713. 



