THE PALAONTOLOGY OF PLYMOUTH, 205 
merate of Torbay, with the felspathic trap noted by me immediately 
adjoining. My attention has likewise been called to the fact that 
Mr. J. C. Bellamy mentions the existence of submerged forests at 
Bovisand, Sandy Cove, and in the Laira. I may also add that Mr. 
Pengelly, F.R.8., 1s of opinion that the Dartmoor Granites are not, 
as he formerly held, of three periods, but of two—the common 
granites and the later elvans. 
Let me remind you of the general facts stated in my former 
paper:—that the rocks of this locality are Middle Devonian; have a 
prevailing southerly dip; and that their order, read by the existing 
conditions of superposition, is: 1, slates; 2, limestone; 3, slates 
and sandstones; while trappean rocks, some contemporaneous and 
some intrusive, also occur, with occasional ash beds. The cleavage 
of the slates, as well as the bedding, partakes of the general 
southerly dip. 
The northern slate rocks do not locally contain any fossils. Near 
Saltash, St. Stephens, and at other points between these places and 
Doublebois, they yield, however, as Dr. Holl has shown, Pleuro- 
dictyum problematicum, Fenestella antiqua, Cyathophyllide, Atrypa 
desquamata, Bellerophon bisulcatus, Orthoceratites, Spiriferse, and 
Phacops latifrons and punctatus. The. absence of fossils in this 
immediate locality is therefore probably due to special local causes. 
The Plymouth limestone is the main storehouse of the local 
paleontology. Originating clearly enough in what was once a 
fringing coral reef; in its origin and constitution it is essentially 
organic. 
The rocks on the south of the limestone are of a more compli- 
cated character than those on the north. Taking the section on the 
east of the Sound, from Mount Batten onwards, it will be seen 
that slates, limestones, shales, grits, ash beds, and sandstones 
alternate with each other in very remarkable fashion, while faults 
and contortions by no means simplify the riddle. These rocks in 
part—the shales and limestones—are largely fossiliferous. 
In the variety of their organic remains the Plymouth rocks are 
not so rich as some of the other limestone districts of South Devon 
——Wolborough and Barton for example; but the species that do 
occur are for the most part abundant. The leading peculiarity is, 
that while at the western end of the limestone (that is to say, at 
the Dockyard, Mount Wise, and in the quarry behind St. George’s 
Hall) mollusks of various kinds occur, at times in great profusion, 
