PLATE XIX. 



Fig. Page. 



Cheirurus (Sphaerocoryphe) thomsoni, sp. nov. 146. 



1. Nearly complete individual (head-shield laterally compressed). x 2. Starfish Bed, 



Thraive Glen. Mrs. Gray's Collection. 



2. Pygidium, with last thoracic segment fused with it. x 2|. Same locality and Collection. 



3. Ditto, x 2. Balclatchie. Same Collection. 



4. Ditto. Imperfect. X 2L Dow Hill. Same Collection. 



o. Head-shield of variety ? x 2. Balclatchie. Same Collection. (Figured by Nicholson 

 and Etheridge, op. cit., fasc. i, pi. viii, fig. 9, as Staurocephalus ? unicus.) 



6. Left half of head- shield of same variety, x 2. Same locality and Collection. 



7. Imperfect head-shield of same variety, x 2i. Same locality and Collection. (Figured 



by Nicholson and Etheridge, op. cit., fasc. i, pi. viii, fig. 12, as Stauro. ? unicus.) 



Cheirurus (Youngia) trispinosus, Young. 148. 



8. Glabella and occipital segment, x 2|. Penkill. Mrs. Gray's Collection. 



9. Ditto, with right cheek attached, x 2. Same locality and Collection. 



10. Ditto, with nuchal spine. x 1|. Same locality and Collection. 



11. Free cheek. x 2. Same locality and Collection. 



12. Axial ring of thorax, x 2£. Same locality and Collection. 



Cheirurus, sp. ind. (a). 149. 



13. Hypostome. x 5. Dow Hill. Mrs. Gray's Collection. 



Cheirurus, sp. ind. (b). 150. 



14. Hypostome. x 5. Balclatchie. Mrs. Gray's Collection. 



Cheirurus bimucronatus (Murchison). 138. 



15. Pygidium. x 2. Woodland Point. Mrs. Gray's Collection. 



Pliomera, sp. 153. 



16. Pygidium. x 3. Auchensoul. Mrs. Gray's Collection. 



Phacops (Pterygometopus) brongniarti, Portlock. 154. 



17. Nearly complete individual, x 2. Dow Hill. Mrs. Gray's Collection. 



18. Pygidium. x 2. Same locality and Collection. 



Phacops (Phacopidella) elegans (Sars and Boeck). 154. 



19. Head-shield, x 2. Bargany Pond Burn. Mrs. Gray's Collection. 



20. Pygidium. x 3. Woodland Point. Same Collection. 



21. Free cheek, x 2 J. Newlands. Same Collection. 



22. Head-shield, x 2.1. Same locality and Collection. 



23. Complete individual. X 4. Same locality and Collection. 



