Mr. E. H. L. Schwarz on CoccoUths. 



343 



lith) transforming itself into a cyatliolith (reproductive stage) ; 

 the granular ring, which 1 have not observed in my fossil 

 forms, being protoplasmic, and the outer ring the commence- 

 ment of one of the cups. Still following Hgeckel, we see that 

 the internal discolith then divides (fig. 5), and traces of the 



Q Q B D 



I, a '3 lit IS 



it 3.<f 



Figs. 1-7. — After Hisckel. 1. Incomplete form. 2. Fully formed disco- 

 lith. 8. One -with the granular ring. 4. Commencing cyatho- 

 lith : a, outer ring ; b, granular ring ; c, mark-ring ; e, JMark- 

 feld; d, central point. 5. One with dividing discoUth and 

 portion of the larger cup forming. 6, 7. Cyatholiths. 



Figs. 8, 9. — Coccolithus oceanicKS, the mature form (discolith). 



Fig. 10. — Young discoliths just released from the cyatholith (cocco- 

 sphere). 



Figs. 11, 12. — Two positions of the fully formed cyatholith. 



Figs. 13-15." — Cyatholith with the rim broken off. 



Fig. 16. — Diagrammatic section through a cyatholith. 



Figs. 17-21. — Successive stages in the divisicin of the discolith. 



Figs. 22-26. — A cyatholith containing four discoliths, which was turned 

 over and then dissolved with acetic acid, setting the contents 

 free, which were then moved about. 



Fig. 27. — Nodosaria caUmorpha^ Eeuss, associated with coccoliths in the 

 clay containing Schlotheimia angulnta (Schl.). 



second, larger cup appear ; tlie two cups are then completed, 

 and the dividing discolith is shut in between them, the 

 smaller cup forming a lid to the cavity of the larger (figs. 11, 

 12, 16). In the early stages of division the form is still oval 

 (figs. 17, 18), but soon the cups become rounded, and the 

 divisions go on irregularly till there are sixteen or more 

 embryonic discoliths ; intermediate forms with four, five, six, 

 seven, &c. are frequent. In the later stages the cups of the 

 cyatholith become brown and opaque, and finally, failing to 

 adhere, they set free the baby discoliths in a mass (fig. 10) ; 

 the empty shells are seen in almost every slide. 



