206 T. RUDDY ON THE CAMBRIAN AND 
graphical position and have the same lithological character as the 
Hirnant beds; but I am as yet unable from fossil evidence to con- 
nect these two beds of grit. I think, however, that I have proved that 
the Hirnant grits and limestones are not confined to the Hirnant 
valley, but can be traced to the north of the river Dee. 
Fig. 5.—Section at Cefn-bwlan. 
Afon 
Cefn-bwlan. Blaenycoed. 
1. Lower Llandovery Grits and shales (?>=Hirnant Grits). 
2. Soft blue slaty shales, 50 feet, like those above the Hirnant Grits; but the 
Hirnant Grits, near the river Dee, are 300 feet thick, and in Hirnant valley 
not less than 250 feet. 
3. Tarannon shale, about 150 feet. 
This Section is taken at the south side of the fault of Cefn-bwlan, near 
the head of the Llanwddyn valley in Montgomeryshire. 
Section VI. (fig. 6).—Starting from the Railway Station at Cynwyd, 
a little village west of Corwen, we ascend the mountain road by the 
side of Afon Trystion, passing the picturesque gorge and falls of 
Cynwyd, until we arrive at a small square plantation on the road- 
side about two miles from the village. Here we are sure to find 
plenty of Trilobites, chiefly Calymene senaria, beautifully preserved 
in a dark and light grey shale with a few small calcareous concre- 
tions (No. 11). Associated with the Trilobites are numbers of 
bivalves, chiefly of small size, a few specimens of Conularia, an 
occasional Rhaphistoma and Ctenodonta, with plenty of the narrow 
branching forms of Favosites (Stenopora) fibrosus. 
It was here I found a single shell of a small but beautifully 
sculptured Strophomena, probably either St. antiquata or corrugatella. 
This is undoubtedly the equivalent of the Bala Limestone. 
Proceeding to the upper road which leads towards Moel Ferna, we 
pass over upwards of 200 feet of shale (No. 10) containing few 
traces of fossils, until we get to Bwlch-y-Gaseg. At the foot of 
the hill we find a thin bed of shale (No. 9) containing Remopleurides 
Colbii, Calymene senaria, Trinucleus seticorms, and T. concentricus 
in great perfection; also Orthoceras vagans, which is chiefly con- 
fined to the limestone at Rhiwlas and the circular outlier above 
Llangower, south of Bala Lake. In this bed I found several 
specimens of Conularia of various species. The next zone (No. 8) is 
easily known by the abundance of corals which it contains, many of 
the species appearing for the first time in the Bala beds. Associated 
with the corals are many other rare and beautiful fossils (see list 
appended to figure). Zone No. 7 is of a more sandy and massive 
character ; here the corals are scarcer and smaller, but an abundance 
