Fig. 18. Horizontal section of the eye 60/1. Spec. CD. » 19. Vertical section of the same passing obliquely through two rows of prisms 60/1. » 20. Fragment of the same eye with entire prisms 30/1. » 21. The hypostoma seen from the inside 3/1 from Sandvik, Öland. » 22. The left macula 12/1. Spec. BO. From Vestanå, Östergötland. =Asaphus raniceps= DALM. p. 40. Fig. 23. The left macula 12/1. Spec. BV. » 24. Horizontal section of right macula 60/1. Spec. BY. » 25. Vertical section of a macula 60/1. » 26. A similar section of a macula (_a_) in the longitudinal axis of the hypostoma 12/1. Exterior surface at right. All from Östergötland. =Asaphus= sp. p. 41. Fig. 27. A portion of the eye near the superior margin 30/1. » 28. Horizontal section of the eye 60/1. » 29. Horizontal section near the inferior margin 60/1. » 30. Vertical section near the superior margin 60/1. All figures from specimen CE. From Gotska Sandön. K. Sv. Vet. Akad. Handl., Bd 34, No 8. Lindström: Trilobites. Pl. I. [Illustration] G. Liljevall del. Ljustryck af Chr. Westphal Stockholm. Pl. II. =Asaphus= (Isotelus) =gigas= J. HALL p. 42. Fig. 1. The right macula surrounded by terrace lines 3/1. » 2. Horizontal section of a macula with a part of the test 60/1. » 3. Vertical section of the same, the surface of the outside upwards 60/1. All specimens from Cincinnati, Ohio, Hudson River group. Spec. BU. =Bronteus irradians= LINDSTRÖM. p. 43. Fig. 4. The hypostoma 4/1. » 5. The left macula 12/1. Specimen from Gotland, Löjsta. =Bronteus laticauda= ANG. p. 44. Fig. 6. Horizontal section of the cephalic eye 20/1. » 7. The same highly magnified 250/1. » 8 & 9. Vertical sections of the cephalic eyes 20/1. In fig. 8 with integument, in fig. 9 decorticated. » 10. Hypostoma. Specim. N. 2/1. » 11. The right macula, from the outside. Spec. O. 12/1. » 12 & 13. Left maculæ, casts of the interior surface 12/1. Specimens from Dalecarlia. _Bronteus platyactin_ ANG. p. 43. Fig. 14. Vertical section of cephalic eye, _a_ the eye. _b_, cheek 20/1. » 15. Hypostoma 2/1. » 16. The same from the interior surface. Sockets of the maculæ sunk in the shell 2/1. » 17. The right macula 12/1. » 18. Portion of the eye on the macula in transmitted light 20/1. » 19. The same more magnified 60/1. Specimens from the stratum _b_. Wisby, Norderstrand. =Bronteus polyactin= ANG. p. 8.