Part 24

=Cyrtometopus clavifrons= DALM. p. 49.

Fig. 17 & 18. Horizontal sections of cephalic eyes 60/1. » 19. Vertical sections of cephalic eyes and a part of the cheek 20/1. » 20. A highly magnified portion of the eye in vertical section 60/1. » 21. Hypostoma, 3/1 the anterior wings completed after another specimen. From Östergötland.

=Cyphaspis elegantula= ANGELIN p. 52.

Fig. 22 & 23. Horizontal and Vertical sections of cephalic eyes 60/1. Diameter of facets 0,03 mm. » 24 & 25. Hypostomas from the front side and in side view 8/1. Upper Silurian, Gotland.

=Ctenopyge pecten= SALTER p. 29.

Fig. 26. The head shield, the free cheeks added from other specimens 4/1. » 27. A free cheek, viewed without foreshortening, as in its natural position 4/1. Alumschists of Andrarum, Scania

=Ctenopyge= n. sp. (LINNARSSON, Geol. För. Förhandl. 1880, pl. VI, figs. 14, 15) p. 29.

Fig. 28. A free cheek 6/1. » 29. Surface of the eyes, near the suture 30/1. » 30. The same next the free cheek 30/1. Andrarum.

=Sphærophthalmus alatus= ANG. p. 29.

Fig. 31. The head shield; the free cheeks have been added 8/1. » 32. A free cheek without foreshortening 8/1. » 33 & 34. Horizontal and Vertical sections of cephalic eyes 100/1. The cornea nearly 0,01 mm. in thickness. Andrarum.

=Peltura scarabæoides= WAHLENB. p. 29.

Fig. 35. The head shield; the free cheeks added 2/1. » 36. A free cheek, not foreshortened 4/1. » 37. A cast of the inside of the cephalic eye 20/1. » 38. A portion of the cephalic eye from the inside 60/1. » 39. A portion of the same in transmitted light 100/1. » 40. Vertical section of an eye 100/1. The rock on the inside. » 41. A similar one passing through two rows of lenses, the one behind the other. The rock on the outside 100/1. » 42. A hypostoma 8/1. Andrarum.

=Dalmanites imbricatulus= ANGELIN p. 53.

Fig. 43. The cephalic eye near the inferior margin 20/1. » 44. Vertical section of the same and a portion of the free cheek 60/1. The lenses are almost contiguous and the interspace between them is formed by the common test of the body, which is perforated by longitudinal tubes.

=Dalmanites obtusus= LINDSTR. p. 53.

Fig. 45. Horizontal section of cephalic eye near the inferior margin 30/1. » 46. Vertical section, the interspaces being in this wider than in the preceding 60/1. From Gotland.

=Dalmanites vulgaris= SALTER P. 54.

Fig. 47. Part of the cephalic eye near the inferior margin 20/1. » 48. Horizontal section near the surface at the inferior margin 30/1. » 49. A tangential section, so that the inferior part is below the lenses where the peculiar radiating structure is seen in horizontal section 30/1. » 50. Vertical section of a small Specimen, fibrous appendices below the lenses 30/1. » 51. Hypostoma 2/1. » 52. The right macula 12/1. English specimens from Dudley, Shropshire.

=Dysplanus centrotus= DALMAN p. 55.

Fig. 53 & 54. Horizontal and vertical sections of an eye 60/1. » 55. Hypostoma 3/1. » 56. The anterior wing of the hypostoma seen in foreshortening 6/1. Specimen AX from Westanå, Östergötland.

=Dysplanus ladogensis= HOLM p. 55.

Fig. 57. Hypostoma 3/1. » 58. The same, seen from the side 3/1. Specimen AI from Östergötland.

K. Sv. Vet. Akad. Handl., Bd 34, No 8.

Lindström: Trilobites. Pl. III.

G. Liljevall del.

Ljustryck af Chr. Westphal Stockholm.

Pl. IV.

=Chirurus speciosus= HIS.