PLATE I. 



DEVONIAN AND LOWER SILURIAN. 



Fig. 



] — 4. Phacops granulatus, Munster. From Upper Devonian Rocks. Fig. 1, Newton Bushell. 



(Mr. Pengelly's cabinet.) Figs. 2, 3, 4, Petherwin, Cornwall. (Mus. 

 Pract. Geology.) Fig. 4 a is fig. 4 enlarged. 



5 — 7. „ Icevis, Munster. Knowl Hill, near Newton Bushell. (Figs. 5, 6, Mr. Pengelly's 



cabinet. Fig. 7, Mr. Vicary's collection.) 



8. „ cryptophthalmus,EMMTi.'! Newton Bushell. (Mus. Pract. Geology.) 



9 — 15. ,, latifrons, Bronn. From the Uppermost Devonian or Pilton Group, near Barnstaple. 



Figs. 9, 10, somewhat distorted. (Mus. Pract. Geology.) (Fig. 11, 

 cabinet of Mr. Townskend Hall.) Fig 11 a, eye, with spaces between 

 the lenses marked out into hexagonal areae on the inner cast. Fig. 12, 

 specimen with very prominent cups in the inner cast, i. e. with thickened 

 cornea. Fig. 13, specimen with thinner cornea and less prominent cups. 

 Fig. 14, Baggy Point, N. Devon. (Mus. Pract. Geol.) 



16. ,, „ Variety with narrower axis and more side ribs. Newton Bushell. (Mus. 



Pract. Geology.) 



17 — 19. Phacops punctatus, Steininger. Liskeard. (Figs. 17, 18, Mr. Pengelly's cabinet. Fig. 19, 



Mus. Pract. Geology.) 



„ Brongniartii, Portlock, Montgomeryshire, Lower Silurian. (Mus. Pract. Geology.) 



,, ,, From Tyrone. Portlock's figured specimens. 25 a. Magnified. 



„ ,, Variety or 9 form. (P. Dalmani, Portlock, figured specimen.) 



Phacops incertus, Deslongchamps. Lower Silurian pebbles of Budleigh Salterton, S. Devon. 

 (Mr. Vicary's cabinet.) 



,, Jukesii, Salter. N. Wales. (Mus. Pract. Geology.) Caradoc Rocks. 



,, alifrons, Id. From N. Wales (copied from figures in the Woodwardian Synopsis). 



„ „ ,, N. Wales (from specimens in the Mus. Pract. Geology). Caradoc. 



„ rnimus, Id. Quartzite of Gorran Haven, Cornwall. (Mus. Pract. Geology.) Llan- 



deilo Rocks ? 



„ apiculatus, Salter. Horderley, &c, Shropshire. Caradoc. (Mus. Pract. Geology.) 



„ Jamesii, Portlock. Figured specimens, Waterford. Caradoc. (Mus. Pract. Geology.) 



,, „ „ Tail of the same, magnified. 



,, obtusi-caudatus, Salter. Fine specimen in the Woodwardian Museum, from Coniston 



Flags. Caradoc Rocks. 



43 — 45. „ „ Variously distorted specimens. (43, 44, Brit. Mus. 45, Mr. Edgell's 



cabinet.) 



20. 





21- 



-25. 



26. 





27, 



28. 



29, 



30. 



31, 



32. 



33, 



34. 



S5. 





36- 



-38 



39- 



-41. 



41 



a. 



42. 





