NOTES AND QUERIES. 
67 
Upper coal-measures. 
Middle coal-measmes. 
Peunant grit. 
Lower coal-measures. 
Gannister beds. 
Millstone grit (farewelirk 
Upper limestone shale"" 
(Yoredale rocks). 
Carboniferous (or moun- 
tain) limestone. 
Lower limestone shale. 
Upper Devonian and 
Petherwin limestone. | 
Middle Devonian lime- 
stone and cornstones. 
Lower Devonian. J 
Tilestone. 
Upper Ludlow. 
Aymestry limestone 
Lower Ludlow. 
Wenlock limestone. 
Wenlock shale, sandstone 
and flags. 
"NVoolhope limestone 
Denbighshire grits, 
shales, slates, and 
flags. J 
Tarannon shale (or pale~^ 
slates). I 
Upper Llandovery rock }■ 
i (May Hill sandstones) | 
(Fentamerus beds). J 
- o 
o ^ 
"1 fi. CD 
log 
\n 
C O 
J --^ 
!3| 
1 
Lower Llandovery rock. 
Caradoc or Bala beds. 
UpperLlandeilo flags and"! ' o 
limestones. r J ^ 
Tremadoc slates. j 
Lingula beds. 
Harlech grits, etc. 
Purple slates and grits 
(St. David's). 
Llanberis grits and slates. ^ 
Red sandstone, conglo- 
merate of Scotland. 
Gneiss of the Lewis 
Basalt. 
Hornblende rock. 
Porphyry. 
Felstone. 
Trappean rock (Devon and Corn- 
wall). 
Diallage. 
Hypersthene rocks. 
Serpentine. 
Elvan dykes. 
Greenstone (Diorite). 
Ashy slate, and Felspathic ash. 
Syenite. 
Granite. 
Scotch System of Carboniferous Rocks. 
Upper coal-measures = •{ 
fEquivalent to 
British middle 
! coal - 
Moor rock 
measures, 
Pennaut grit, 
lower coal-mea- 
sures. 
^Millstone grit 
(Farewell rock). 
Upper limestones 
Edge-coals series 
Lower limestones 
=1 
Sandstones, shales, 
Burdie House lime 
stone 
Upper lime- 
stone shale 
(Yoredale 
rocks), CarboHi- 
I ferous lirae- 
stone. 
{Lower lime- 
stone shale. 
T^oTE OX Pteeaspis. — Sir, — I hope you will allow the following re- 
marks, occasioned by the notices of Pteraspis in the ' Geologist' for No- 
vember, December, and January last, a place in an early number. 
In the spring of 1861, from amongst a lot of fragments laid aside by the 
workmen in a quarry in the hill immediately to the north of the Bridge of 
Allan, I picked up a fine head of Cephalaspis Lyelli and two tolerably 
complete heads of Pteraspis ; and since that time I have, from the same 
place, procured another less perfect specimen of the latter genus. To this 
discovery I referred in a paper read to the Geological Society of London 
in July of the same year ; and thus, I believe, I was the first to show that 
our Scottish rocks containing Cephalaspis also possessed the nearly allied 
genus Pteraspis. 
Of the most perfect of these three heads, both the cast and its opposite 
