Coccospliercs and the Origin of Coccolitlis. 3]. 5 



}3ecorae interlocked with those of its neighbours. By this intercala- 

 tion an increase of the volume of the sphere is provided for. 



10. The oval and dished form of the coccoliths are adaptations to 

 allow of the rearrangement of the older coccoliths on the extrusion of 

 a new one, and of suitable interlocking on the spherical surface. 



EXPLANATION OF PLATE 3. 



All the figures are drawn by means of a camera lucida from specimens obtained 

 at Valencia and Waterville, Co. Kerry, except Fig. 1. 



Fig. 1. — Coccosphere, x 1400, drawn from a fresh specimen captured September, 

 1897, in Killiney Bay. 

 „ 2. — Fragment of small coccosphere composed of four interlocking coccoliths. 

 X 1250. 



„ 3. — Microtome section of coccosphere, showing an early stage in the develop- 

 ment of an internal coccolith. x 900. 

 „ 4. — Microtome section of coccosphere, showing coccoliths in section, x 1120. 

 Figs. 5 and 6. — Single coccolith in section and plan. 



Fig. 7. — Microtome section of coccosphere, showing mature internal coccolith. 

 X 1120. 



„ 8. — Microtome section of coccosphere, with partially developed internal cocco- 

 lith. X1120. 



„ 9. — Microtome section of coccosphere after solution of coccoliths and staining 

 with Delafleld's haematoxylin. x 1120. 

 10. — Outer pellicle remaining over after the coccoliths of a coccosphere are 

 dissolved in acid glycerine jelly and stained in aniline blue, x 900. 

 Figs. 11 and 12. — Coccospheres after prolonged action of picric nigrosine, x 900, 

 showing the slimy layer, stratified membrane, and the nucleus within 

 the latter. 

 Fig. 13.— Same as 12. x 1250. 

 „ 14. — Coccosphere partially dissolved in picric nigrosine, showing the internal 



coccolith in early stages of solution. 

 „ 15. — Optical section of a coccosphere, x 900. Within the external coccoliths 

 are seen the constricted nucleus and a nearly mature coccolith in 

 contact with the nucleus. The specimen is stained with aniline blue 

 soluble in alcohol. 



„ 16. — Optical section of a coccosphere after treatment with liquor iodi. x 900. 

 Inside the coccoliths is seen a problematical trilobed body. 



„ 17. — Optical section of a coccosphere, showing nucleus in contact with a com- 

 pletely developed internal coccolith, stained in aniline blue soluble in 

 water, x 900. 



„ 18. — A coccosphere showing an internal coccolith immediately beneath the 

 external coccoliths. x 900. 



VOL; LXVii 



