78 



LIXDSTHOM. VISUAL (»HGANS ()K THE TKILOBITKN. 



PI. II. 



Fig. 



Fis. 



Fig. 



Fie. 



Fig. 



Asaphus (Isotelus) gigas J. Hall p. 42. 



1. The right macula surrounded by terrace 

 lines :! i. 



2. Hori/ontal section of a macula witli a part 

 of the test ,; " i. 



:'). Vertical section of the same, the surface of 

 the outside upwards 60 /i. All specimens from 

 Ciiiciiuiati, Ohio. Hudson River group. Spec. 

 BU. 



Bronteus irradians LlNDSTR. p. 43. 



4. The hypostoma ' i. 



5. The lett macula '- i. Specimen from Got- 

 land, Lö.jsta. 



Bronteus laticauda An<;. p. 44. 



ii. Horizontal section of the cephalic eye ao i. 



7. The same highly magnified 260 /i- 



8 & 9. Vertical sections of the cephalic eyes 



-" i. In fig. 8 with integument, in fig. 9 



decorticated. 



10. Hypostoma. Specim. X. Vi. 



11. The riglit macula, from the outside. Spec. 

 O. 12 .. 



12 & 13. Left maculse, casts of the interiör sur- 

 face 12 i. Specimens from Dalecarlia. 



Bronteus platyactin Ang. p. 43. 



14. Vertical section of cephalic eye, u the eye. 

 b cheek 2 %. 



15. Hypostoma 2 /i. 



16. The same from the interiör surface. Sockets 

 of the macula' sunk in the shell 2 /i. 



17. The right macula 12 /i. 



IM. Portion of the eye on t lie macula in trans- 

 mitted light 20 /i." 



19. The same more magnified ,; " i. Specimens 

 from the stratum b. Wishy, Norderstrand. 



Bronteus polyactin ANG. ]>. 8. 



20. Hori/ontal sectioii of cephalic eye '-'" i. 



21. Vertical sectioii of the same 60 /i. 



22. Hypostoma i /i. 



23 — 25. Samples of right maculse 2 " i. 



26. Horizontal section of macula. the portion 

 bearing the lenscs 20 /i. 



27. Vertical sectioii of the same ''" i, a the 

 Lenses. Specimen from Stora Carlsö. 



Bronteus sp. p. 45. 



Fie. 28. Hypostoma */i. 



29. The right macula 12 /i. 



30. A portion of the lenscs on the macula in re- 

 flected light 30 /i. The lenses are only faintly 

 convex and encased in a white frame. The 

 diameter of the largest lenses 0,oe millim. 

 Specimen from Länsa. Fårö. 



Bumastus barriensis Murch. p. 4 ii. 



BMg. 31. Hy]tostoma */i. 



32. The right macula 12 /i. Specim. CU from 

 Wishy. 



Bumastus sulcatus LlNDST. p. 4G. 



Fig. 33. Horizontal section of a cephalic eye 20 i. 

 ■<> 34. The same magnified 60 /i. 



35. A similar, near the interiör margin and elose 

 to the surface. a the eye, b cheek 60 /l. Com- 

 pare fig. 38. 



36. Vertical sectioii of the cephalic eye near the 

 suture 20 i. 



37. The same, more magnified 60 /i. 



38. A similar, near the inferior margin, " eye, 

 b cheek G0 'i. 



39. Cast of the interiör surface of ;i hypostoma 



"A. 



40. The same seen from the side. 



Originals to tigs. 33—38 from Sanisugn, 

 Othem, Gotland, tigs. 39 & 40 from Stora 

 Vede, Follingbo, Gotland. 



Bumastus sp. p. 47. 



Fig. 41. Horizontal sectioii of cephalic eye, near the 

 interiör margin, a eye, b cheek, ''" i. 

 » 42. Vertical section of the same B0 i. 



43. A similar near the inferior margin, « eye. 

 h cheek, m ;i. 

 » 44. Hypostoma ' i. 



45. Side view of the same. 

 4i'). The right macula 12 /i. Specimens from Korp- 

 klint near Wishy. 



Bumastus sp. p. 46. 



Fig. 47. Hypostoma i /i. 



4 8. The riglit macula 12 /i. Specimen from Klints, 

 Othem, Gotland. 





