124 BALA FOSSILS. 
quarry of Pen-y-glog, situated at the base of the Wenlock beds, 
where Grapfolithus priodon is in abundance. The exact locality 
of the other species is unknown. 
The species of Fenestella given in both of the above lists are 
also very doubtful. I very much question whether we have a 
true Fenestella in our North Wales Bala beds. I have seen 
three so-called species (Fenestella assimilis, F. subantiqua, and 
F. regularis) in the London Museums, but they were only 
specimens of Phyllopora and Ptilodictya. Mr. SHRUBSOLE con- 
firms this opinion as to the absence of Fenestella. 
The collecting of the above, and the working up of the 
various zones, has been the careful labour of over ten years. 
A few other things remain to be classified when better speci- 
mens are found. 
Here I wish to acknowledge the assistance I have received 
from Mr. SHRUBSOLE in working out the fossils, more particu- 
larly of the Glyn Ceiriog district, with which he has long been 
familiar. 
