16 EXPLANATION OF THE PLATES. 
PLATE VII. 
FOSSILS OF THE LLANDEILO ROCKS. 
CRUSTACEA.— TRILOBITA. 
+ 
Fia. 1.—a, b, ec. AgNostus M‘Coyrm, Salter. 
Geol. Surv., Dec. 11, pl. xii., fig, 8; Siluria, third edition, pl. iil., figs. 7, 8; 
Memoirs Geological Survey, vol. iii., p. 297, pl. xiii., figs. 8 and 8 a 
being transferred from figs. 6 and 6 a of the plate in the Decade above 
cited. 
a. Original. The head only; in Museum, Geological Survey of Ireland, 
from black shales of the upper Llandeilo, Builth ; on the same slab is a frag- 
ment of the cheek margin of Ogygia Buchit. 
Our figure, taken from the specimen named as above, is somewhat different 
from that in the Decade before referred to; the collection in Ireland did 
not possess a tail, which is therefore copied from the Decade. It is stated 
by Mr. Salter to be a frequent fossil in the black Llandeilo Flags of Builth, 
in Radnorshire, and Shelve, in Shropshire, accompanying the Ogygia 
Buchii and Ampyx nudus. 
Upper LLANDEILO FLAGs.—Builth, Radnorshire ; Llandeilo, Caermarthen- 
shire ; Marrington, Wilmington, and Shelve, Shropshire. 
Fig. 2.— ASAPHUS TYRANNUS, Murchison. 
Siluria, third edition; pl.i., figs. 4.and 5, pl.ii., fig. 1; Memoirs Geolo- 
gical Survey, Dec. 11, pl. v., fig. 1; and vol. iii., p. 312, pl. xiii, figs. 
1-5. British Trilobites, J. W. Salter, in Pal. Soc., 1866, p. 149, pl. 
XXi., XXll., figs, 5-12. 
Reduced one-third from fig. 1, pl. v., in the above Decade. (The parts 
wanting in this specimen, as in other figures, are restored in outline where 
practicable.) Respecting this fine Trilobite Mr. Salter remarks—“ It is a 
truly characteristic species of the Upper Llandeilo age, as common at 
Llandeilo as O. Buchiz,” Decade 2, p. 3; and Memoirs Geological Survey, 
vol. iil., p. 312. 
LLANDEILO Fracs.—Abundant in South Wales; Llandeilo, and many loca- 
lities in Caermarthenshire ; in Pembrokeshire ; Musclewick Bay ; Llam- 
peter, Felfrey ; Narberth; Mydrim; and Lann Mill. In Shropshire, Mea- 
dowtown, Shelve, &e.; in North Wales, Craig-y-glyn, near Llanhaiadr 
in the Berwyns. Pal. Soc., p, 152. 
