76 



LINDSTRÖM, VISUAL ORGANS OF THE TRILOBITES. 



Pl. I. 



Fig. 



Fig. 



Fig. 8. 



9. 



» 10. 



11. 



12. 



13. 



14. 

 15. 



Acidaspis crenata Emmr. p. 35. 



1 & 2. Vertical sections of the eye 60 /i. 



3. The outside of the hypostoma G /i. 



4. The anterior margin of the hypostoma, show- 

 ing one of the clubshaped spöts in transmitted 

 light "°/i. 



5. The granulations of the hypostoma in trans- 

 mitted light 80 /i. 



6. Vertical section of the hypostoma with gra- 

 nules G0 /i. 



Specimens from Djupvik, Eksta. 



Agnostus glandiformis Angelin p. 35. 



7. Vertical section of a part of a rolled up spe- 

 cimen 8 /i. Specimen signed CQ. Andrarum, 

 Scania. 



Asaphus expansus L. p. 39. 



Horizontal section of the eye near the upper 

 margin, a. The surrounding spongious zone, 

 b. The surface of the eye with lenses 6 %- 

 Spec. CG. 



Horizontal section from the centrum of the 

 eye 6 %. Spec. CF. 



Horizontal section near the interiör margin, 

 a the eye, b marginal zone, c a portion of 

 the cheek 60 /i. Specim. CF. 

 Vertical section near the inferior margin 6 %, 

 same specimen as in fig. 10. 

 Eye fractured vertieally showing regular prisms 

 in the eye (a) and irregular ones in the mar- 

 ginal zone (b) 30 /i. 



Part of the hypostoma with the macula 12 /i. 

 The right macula from the inside 12 /i- 

 A vertical section across the hypostoma, aa 

 the maculse 8 /i. 



Fig. 



Fig. 



Fig. 



16. A similar one of the macula at left in the 

 preceding figure 60 /i. 



17. The right macula from the outside in trans- 

 mitted light 60 /i. Sp. BQ. 



Asaphus fallax Dalm.? p. 41. 



Horizontal section of the eye e0 /i. Spec. CD. 

 Vertical section of the same passing obliquely 

 through two rows of prisms 6 %- 

 Fragment of the same eye with entire prisras 



The hypostoma seen from the inside 3 /i from 

 Sandvik, Öland. 



The left macula u /i. Spec. BO. From Ves- 

 tanå, Östergötland. 



Asaphus raniceps Dalm. p. 40. 



The left macula 12 /i. Spec. BV. 

 Horizontal section of right macula 60 /i. Spec. 

 BY. 



Vertical section of a macula 60 /i. 

 A similar section of a macula (a) in the 

 longitudinal axis of the hypostoma 12 /i. Ex- 

 teriör surface at right. 

 All from Östergötland. 



Asaphus sp. p. 41. 

 Fig. 27. A portion of the eye near the superior raar- 



18. 

 19. 



20. 



21. 



22. 



23. 

 24. 



25. 

 26. 



28. 

 29. 



gin 30 /i. 



Horizontal section of the eye 60 /i. 



Horizontal section near the inferior margin 



60/ 



71. 



30. Vertical section near the superior margin 



00/, 



All figures from specimen CE. From Gotska 

 Sandön. 



