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Univrrxihi of California PiibliraUoiis in Zoology. [Vol.4 



the ends of the horns and less abundantly on the thin ventral 

 plate (figs. 5 and 6). The pla.sma streams out through tliese 

 pores (Schiitt '99) in long filaments and may form an r-xtramem- 

 branous sheet on the outer face of the exoskeleton. Both faces 



fst ap. p. 



r. ant. 



Fig. 5. — Ventral view of Cciatium eugrammum, an anterior schizont 

 after recent division. X 913. 



Pig. 6. — Dorsal view of the same. Eegenerated moiety of the theca 

 shown without pores. X 913. 



Abbreviations — op. p., apical pore; f. p., flagellar pore; fi^. 1.. fission 

 line; I. ant., left antapical; r. ant., right antapical; tr. f., transverse fur- 

 row; V. pi., ventral plate; l'-4', apical plates; l"-4", precingular plates; 

 l'"-5'", postcingular plates; l""-2"", antapical plates. 



of the cellulose wall are thus accessible to action of the cytoplasm 

 in deposition or solution of the material of the wall. 



The thickness of the wall and the extent of its surface differ- 

 entiations in the form of lists, ribs, fins, and rugosities differ con- 

 siderably in different species, ranging from the thin hyaline 



