490 TRANSACTIONS OF SECTION C. 
7. Interim Report on the Geology of Ramsay Island, Pembrokeshire. 
See Reports, p. 151. 
8. Report on the Old Red Sandstone Rocks of Kiltorcan, Ireland. 
See Reports, p. 152. 
TUESDAY, SEPTEMBER 16. 
The following Papers were read :— 
1. The Shelly and Graptolitic Faunas of the British Ordovician. 
By Dr. Gertrupe L. ELwes. 
There are two main types of ‘shelly’ faunas of Ordovician age in the British 
Isles, and each of these can be further subdivided into a number of sub- 
faunas which can be correlated by reference to associated graptolite-bearing 
beds. 
Ordovician Faunas. 
Graptolitic | Shelly 
Graptolite Zones A B 
| z. 5 72 iia we | 
Zone of Cephalog. acuminatus Riciroocmhatac peiacor 
Zone of Dicellog. anceps fauna | Exotic fauna. 4 | 
| 
| Zone of Dicellog. complanatus Calitenes planer 
marginata fauna 
with sub-faunas 
. a . | (a) Chasmeps ; 
Zone of Dicranog. clingani | (6) Asaphus 
| Powisi 
in ee 
Exoticfauna . 3 
| Zone of Pleurog. linearis 
Zone of Climacog. Wilsoni 
Zone of Climacog. peltifer Exoticfauna . 2 
| 
| Ogygia Buchi 
fauna. with 
Asaphus tyran- 
nus sub-fauna 
Zone of Nemag. gracilis 
Zone of Glyptog. teretiusculus | Exotic fauna .1 
Zone of Didymog. Murchisoni | 
-——_____—_—__________——| Placoparia fauna | 
| Zone of Didymog. bifidus | | 
| Zone of Didymog. hirundo | 
[= Ogygia Selwyni 
| fauna 
| Zone of Dichograptus | 
Zone of Didymog. extensus 
The main shelly types may be described as : 
A. Asaphid-Trinucleid-Calymenid fauna, 
B. Cheirurid-Lichad-Encrinurid fauna. 
Evidence suggests that fauna B is an exotic fauna, possibly southern in 
origin, which migrated into the British area. Becoming early established in 
South Scotland, it soon spread west into Ireland, but did not dominate the whole 
British area till Ashgillian times. 
