164 
fossilized in situ. From the sedimentological and bryozoan evidence 
this latter interpretation is preferred. However, the possibility that 
the fauna represents an in situ brachipod community into which 
bryozoans have been washed from adjacent reef slopes cannot be 
excluded. 
i 
COMPARISON WITH OTHER ASBIAN 
FAUNAS. 
ee 
Asbian faunas in the British Isles have received little attention, and 
many species recorded from County Fermanagh have not been 
recorded elsewhere. Bancroft (1984) and Wyse Jackson, Bancroft & 
Somerville (1991) document the faunas of several sites in Britain: 
Ashfell Road Cutting, Cumbria [1 cryptostome species / 7-8 
fenestrate species / several trepostome species / 2 cystoporate spe- 
cies]. 
Odin Fissure, Treak Cliff, Derbyshire [1/8/1/1]. 
Penruddock, Cumbria [1/12/several/2]. 
Redesdale, Northumberland [1/1 1/3/1]. 
Nant-y-Gamar, near Great Ormes Head, north Wales [1/3/5/1]. 
This fauna is somewhat unusual as it is trepostome-dominated. 
Carrick Lough and Sillees River, County Fermanagh [9/49/7/4]. 
These faunas are generally dominated by fenestrates and 
fenestellids in particular, with taxa of other bryozoan orders, par- 
ticularly cryptostomes, being conspicious by their scarcity or apparent 
absence. This may be due to poor preservation, which makes identi- 
fication of delicate cryptostome species difficult. 
The fauna in County Fermanagh encompasses all species re- 
ported from the above localities with the exception of five: Fenestella 
matheri, Septopora cestriensis, Batostomella sp., an undescribed 
species of Leioclema, and Stenodiscus tumida. Fenestella plebeia is 
common to all six localities; Fistulipora incrustans and Hemitrypa 
hibernica occur in five while Fenestella bicellulata occurs in three. 
The importance of the Fermanagh fauna lies in its rich taxonomic 
diversity and reasonable fossil preservation which will allow for 
future comparison with other Asbian faunas. Such investigations 
may reveal that the British and Irish faunas are more diverse than 
hitherto appreciated. 
PATTERNS OF BRYOZOAN ZOARIA 
REPLACEMENT BY SILICA 
Replacement of calcified bryozoan zoaria by silica has allowed for 
easy extraction from their carbonate matrix by acid digestion. The 
large number of specimens obtained in this way allows for detailed 
Figs 105, 106 Patterns of silica replacement in bryozoan zoaria from the 
upper part of the Glencar Limestone (Viséan, Asbian), Carrick Lough, 
County Fermanagh, as illustrated by examples of Fistulipora incrustans 
colonies; 105, BMNH PD9740; 105a, euhedral and sub-hedral 
microquartz replacement of calcite autozooecial skeletal structure, 
producing a thin exterior rim that is usually fuzzy in appearance, 
megaquartz crystals infill the autozooecial chambers, x25; 105b, 
grading of euhedral and sub-hedral microquartz rim into spherulitic 
chalcedony which replaces the remainder of the skeleton (Pattern 2), 
x25; 105¢e, total replacement of skeletal walls and autozooecial chamber 
megaquartz infill by pervasive chalcedony and obliteration of original 
skeletal structure, x25; 106, BMNH PD9741, replacement of crinoid 
ossicle stereom by radial spherulitic chalcedony; typical Pattern 2 to 3 
replacement, x25. 
P.N. WYSE JACKSON | 
