SILURIAN IN NORTH WALES. 
1. 
2. 
3 
4. 
5 
S 
E. 
Moel 
Ferna. 
Denbigh evits. 
Graptolite shales (fossils same as in Sect. L., 
bed no. 14). 
Tarannon shale. 
Soft blue slaty shale (always found under 
the Tarannon shale). 
Hard compact grits occupying the strati- 
graphical position of the Hirnant grits 
and limestone, 15 to 20 feet. 
Shales, containing Leptena sericea, L. trans- 
versalis, Petraia, a few Trilobites, &e. 
Marine sandy bed. Orthisina, Orthis 
crispa, O. flabellulum (large, some with 
branching ribs), O. elegantula, O. calli- 
gramma, O. spiriferoides (scarce), O. bi- 
forata, Atrypa marginalis, Strophomena 
Fig. 6.—Section South-west of Corwen. 
grandis, St. depressa, Lamellibranchs (se- 
veral species), Ambonychia?, Petraia, Bellero- 
phon (like B. perturbatus), Ptilodictya expla- 
nata, and the corals of the next bed. 
8. Coral zone. Favosites fibrosus (branching), 
Nebulipora lens, Retepora Hisingeri (com- 
mon), Fenestella Milleri, Glauconome di- 
sticha, Cheirurus, Calymene, Illenus, Pha- 
cops, Trinucleus, Leptena, Murchisonia, Rha- 
phistoma, Echinospherites balticus, Orthis 
as in bed no. 7. 
9, Shale rich in Trilobites. Calymene senaria, 
Trinucleus concentricus, T. seticornis, Pha- 
cops conophthalmus, Oheirurus bimucro- 
natus, Cheirurus sp. (but C. bimucronatus 
is most common), Lemoplewrides Colbii, 
Bwlch-y-Gaseg. 
Road to 
Llanarmon. 
Conularia 
Conularia (sp. ?=C. levigata), Favosites 
(Stenopora), Encrinites, a few common bi- 
valves. 
10. Marine sandy shales; few fossils. 
200 feet. 
11. Caleareous shales; Trilobites abundant. 
Orthoceras vagans, Sowerbyt, 
About 
Hquivalent of Bala Limestone. Calymene 
senaria, Orthis elegantula, Leptena sericea, 
O. biforata, O. calligramma (small), Conu- 
laria Sowerbyi, Strophomena depressa, Stro- 
phomena sp., Ctenodonta, Rhaphistoma sp., 
Enerinites, Favosites (Stenopora) fibrosus. 
12. Shale. I/enus Davisii, Orthis elegantula, 
Leptena sericea, Favosites fibrosus. 
