PLATE IV. 



UPPER AND LOWER SILURIAN. 



Fig. 



1. Phacops caudatus, var. /3, tuberculato-caudatus. A large and fine specimen in 



Dr. Grindrod's cabinet, Lower Ludlow, Malvern. 



2. „ caudatus, junior. Mr. Mushen's cabinet, Dudley. 



3. 4, 5. „ „ var. y, nexilis. Vinnal Hill, Ludlow. (Mus. P. Geology.) 



6 — 9. „ Weaveri, Salter. Fig. 6, imperfect head from Tortworth. (Mus. P. 



Geology.) Fig. 7, tail, ordinary size, Tortworth. Figs. 

 8, 9, tails of mucronate variety, May Hill Schist, Marloes 

 Bay, Pembrokeshire. (All in Mus. P. Geology.) 



10. Phacops imbricatulus, Angelin ? May Hill Rocks, Presteign. (Mus. P. 



Geology.) 



11,12. „ mucronatus, Brongniart. From near Bala. (Mus. Pract. Geol.) 



13 — 15. „ truncaio-caudatus, Portlock, his original figured specimens. Fig. 13, 



natural size. Fig. 14, restored figure, reduced 

 size. Fig. 15, labrum. All from the Caradoc of 

 Desertcreat, Tyrone. (Mus. Pract. Geology.) 



16,17. ,, amphora, Salter. Grug, near Llandeilo. (Mus. Pract. Geology.) 



1 8 — 23. ,, macroura, Sjogren. From the Caradoc of Acton Scott, &c, Shropshire. 



Figs. 18, 19, adult head and tail. (Ludlow Museum.) 

 Fig. 20, external cast of head, middle age. (Mus. Pract. 

 Geology.) Fig. 21, lajprum (Ludlow Museum), showing 

 the perforation a, which marks the place of the ascending 

 process. Fig. 22, perfect tail, and fig. 23, very young 

 tail, pointed. (Ludlow Mus.) 



24, 25. ,, conophthalmus, Boeck ? Fig. 24, young heads. (Mr. Lightbody's 



cabinet.) Fig. 25,. internal cast of head from 

 Llansantffraid Glyn Ceiriog, N. Wales. (Wood- 

 wardian Museum) ; for figure of tail from same 

 locality, see PL VI, fig. 25. 



