TABLE VI. 



UPPER AND LOWER SILURIAN. 

 UPPER SILURIAN. 



Fig. 



1. Sphterexochus mirus, Beyrich. Dudley. (Mr. Shedden's cabinet.) Young coiled specimen. 



2, 3, 4. „ „ Of various ages. From the Wenlock Shale of Malvern Tunnel. (Dr. 



Grindrod's cabinet.) 



5. A coiled-up specimen. (Brit. Mus., Gray coll.) 5 a. The head, dissected, front view, showing 



the anterior glabella-furrows, and at b the anterior segment, the cheeks connected by the 

 hypostome, without the intervention of a rostral shield, c. The convex eye. d. The 

 lentiferous surface, magnified, the lenses removed. 



6. The same viewed dorsally, and showing the strong basal glabella-furrows, the surface finely 



granular, b. The cheeks. A minute tubercle indicates the place of the head-spines, c. A 

 body-ring, third or fourth, showing the position of the fulcrum (d), and the prominence 

 behind, against which the fulcrum abuts. e. Incurved tip of pleura. /. Last thorax- 

 segment, the fulcrum near the axis. In this and the preceding figure the pleurae are repre- 

 sented as flattened out to show their characters ; they would appear much shorter on 

 viewing them from above, g. The tail, magnified. (Figs, c to g are from Capt. T. 

 Fletcher's Dudley collection, now in the Fitzwilliam Museum, Cambridge.) 



7. 8. Cheirurus articulatus, Munster. A large and a small head from Mr. Pengelly's cabinet. 



From Lammaton, Torquay, in Middle Devonian Limestone. 

 9. „ bimucronatus, Murchison, var. /3. A half-grown but very perfect specimen. 



(Cabinet of Mr. E. Hollier, junr.) Dudley. 

 10. A fine specimen, shortened by pressure, from Mr. Ketley's collection. Same variety, — /3. 



1 1 a, b. A Malvern specimen, cleared by Mr. C. Ketley, and now in his cabinet. It shows the labrum 



and the central mucro to the tail, var. a. 116. Side view of ditto. 



12. Labrum, also from Mr. Ketley's cabinet. 



13. Shows the interior view of the same organ. At a, a, the ascending processes, which are attached 



to the sides of the glabella, b, b. The incurved triangular plates. There is a hollow space 

 under the ascending processes, answering to the lateral notch on the upper surface (fig. 12). 



14. Pleurae of C. bimucronatus, from a specimen in Mr. Mushen's cabinet. The lower figure is an 



internal cast of ditto, copied from the Decades of the Survey, a. The posterior fulcral tubercle. 

 b. The anterior tubercle, c. Free tip of pleura, d. Cast of vertical ridge on interior surface. 



15. 16. Tails of young specimens, var. a. Dudley collections. 



17. Entire young specimen, var. a. (Mr. Mushen.) Dudley. 



18. C. bimucronatus, var. /3, centralis. Dudley. (Mr. E. Hollier, junr.) 



(Figs. 19 — 24 are from the Mus. Irish Industry.) 



19. 20. Phacops nudus, Salter, a, b, c. Fragmentary heads. Fig. d \s c magnified, e. Eye, 



magnified. /. The lenses, magnified. Fig. 20, tails, two specimens. 

 Upper Silurian Limestone, Dingle, Co. Kerry. 



LOWER SILURIAN. 

 21—24. Phacops Bailyi, Salter. Caradoc of Tramore, Co. Waterford. 24 a. Interior cast of tail. 



b. Exterior cast. 



25. „ conopthalmus, Boeck. ? Caradoc, N. Wales. (Cambridge Museum.) 



26. Spheerexochus mirus, Beyrich. Caradoc, Chair of Kildare. (Mus. Pract. Geology.) 



27. 28. ,, boops, Salter. Caradoc. Haverfordwest. Fig. 27 (Mus. P. Geol). Fig. 28, 



Westmoreland. (Cambridge Museum.) 

 29, 30. Amphion pseudo-articulatus, Portlock. Caradoc of Tramore, Waterford. (Mus. Pract. 



Geology.) . 



31. „ benevolens, Salter. Caradoc of Newtown, Waterford. (Mus. Pract. Geology.) 



32. „ pauper, Salter. Caradoc of Tramore. (Mus. Irish Industry.) 



