ADVERTISEMENT TO SECOND FASCICULUS. 
i ios former Fasciculus (published May 1851) contains all the paleozoic Radiata and 
Articulata :—the present contains all the lower and middle palxozoic Mollusca :—and 
the third Fasciculus (now in the press) will contain the upper paleozoic Mollusca, and also the 
paleozoic Fishes—thus completing the paleontology of the British paleozoic rocks, so far 
as the subject is illustrated by the collections I have placed in the Woodwardian Museum. 
When the former Fasciculus was printed Professor M°Coy was absent in Ireland, and 
I had no opportunity of examining the proof-sheets: neither had I, at that time, supplied 
him with any detailed geological information respecting the localities from which the several 
fossils were derived. This want has been since supplied; and in an Alphabetical List (com- 
mencing p. 326, and ending p. 331) of all the lower palozoic localities alluded to in this 
as well as the preceding Fasciculus, each locality is referred to its supposed geological 
place in the general series, agreeably .. a scheme of nomenclature given in the following 
Tabular View. In the same list, and for the express purpose of easy reference, each locality is 
defined by the number which precedes it. 
Tabular View of the British Palwozote System. 
Upper { Permian Series . . . .Divisible into three-groups. 
*** \ Carboniferous Series -Divisible into three or four groups. 
6 Petherwin slate and Clymenia limestone. 
a Marwood sandstone. 
6 Hereford sandstone, marl, and cornstone. 
a Dipterus flags, &e. &. 
6 Dartmouth slate. 
a Plymouth limestone and red grit. Liskeard slate 
| ce Upper Ludlow. 
| 9 Petherwin group a 
8 Caithness group. . 4 
Middle . . | Devonian Series . . 
| 7 Plymouth group... 
6 Aymestry limestone. 
a Lower Ludlow. 
| 6 Ludlow group..... 
Silurian Series ... ¢ 
c Wenlock limestone. 
6 Wenlock shale. 
a Lower Wenlock, or Woolhope, limestone. 
5 Wenlock group... 
Primary or Paleozoic System. 
4 Caradoc group..... Caradoc sandstone, limestone, and shale. 
Lowen. 6 Upper Bala, including the Bala and Hirnant 
3 Bala group....... limestone, shale, flagstone, and conglomerate. 
a Lower Bala, dark slates, flags, and grits. 
Cambrian Series .. . e Arenig slates and porphyry, with one irregular 
it band of limestone. 
2 Festiniog group .--) 5 Tremadoc slate. 
|. Lingula flags. 
b Harlech grits. 
iy ESE Or GROUP ia \ a Llanberis slates. 
Hypozoic and Metamorphic Groups. 
Granite. 
