KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND .32. N:0 i. 



115 



Explanation of the Plates. 



AU flgures have been drawn by Herr G. Liljevall, unless otherwise stated. 



The numbers (VO mark the seale of the enlargement. 



The plates are exeeuted in Herr C. Westphal's phototypie establishment. 



Plate I. 



Heliolites interstinctus L. p. 41. 



Fig. 1. Surface of a speciraen from the Arachno- 

 phyllura stratum near Wisby. ''/i. 



» 2. Longitudiiial section of the same; tabulse a 

 little irregular, an irregular columella on 

 two of the lowest of them. ''/i. 



» 3. Transverse section below the surface of a spe- 

 cimen from the Arachnophyllum beds. "/i. 



» 4. Surface of a specimen with uncommonly small 

 calicles, nat. size. 



» 5 — 6. Transverse sections of the same below the 

 surface, Vi; fig- 5 situated a little higher 

 up than f. 6. 



» 7. Longitudinal section of the same, calicular 

 tube budding out of the coenenchyraa. 



» 8. Longitudinal section of another specimen, from 

 the same stratum; near the top, in the 

 middle of the calicular tube a streak of 

 sectioned columellas is seen; then it is 

 interrupted and a little higher a continua- 

 tion appears; on the right side a narrow 

 septal lamina is sectioned. Vi- 



» 9. Surface of typical specimen from the stratum 

 d near Wisby. Vi- 



» 10. Surface of a specimen with columellas, stratum 

 d near Wisby, nat. size. 



»11. A not fully mature calicle from the same 

 specimen, magnified, showing how the septa, 

 which still are long on the right side, have 

 communicated with the central columella 

 and probably originated it through their 

 union and left it alone, when they have 

 been reduced in size. 



Fig. 12. 



13. 



14. 



15. 



16. 



17. 



Longitudinal section of a specimen from stra- 

 tum a near Wisby, showing how the cali- 

 cular tubes and the coenenchyma arise 

 directly from the epitheca; vestiges of 

 columellas a little higher; to observe is 

 the peculiar wavy line formed by the 

 theca. Vi- 



Part of a speciraen from the stratum a near 

 Wisby, with a new calicle in the act of 

 developing, the large septa discernible ex- 

 cept in the lower right corner; in the 

 centre there is still coenenchyma out of 

 which the columella is formed låter; the 

 central line between the walls of the 

 coenenchymal tubes clearly visible, and 

 also in the septa. ^/i. 



Transverse section of a specimen with divided 

 columella, small, partially absorbed septa. 



Vi. 



Longitudinal section of a specimen from 

 stratum d, near Wisby, showing how 

 two long calicular tubes proceed from 

 the coenenchyma; long columnar streaks 

 in the middle; columella at times evi- 

 dently divided or branching, origin ot 

 coenenchymal tubes through fission evident. 

 Vi. 



Surface of specimen from a, calicles with 

 irregular septa, the left one had just been 

 forming. ^Ii. 



Specimen from the highest limestone beds 

 of Bara liill, Gotland, as a type for the 



