P.N. WYSE JACKSON 
acanthostyles. Strong undulating ridges and short acanthostyles are 
common in interapertural areas. 
DESCRIPTION. Zoaria form dendroid expansions of unknown maxi- 
mum height and are composed of cylindrical dichotomising or 
bifurcating branches 0.46 mm to 1.12 mm in diameter. 
Autozooecia are arranged in poorly defined longitudinal rows and 
are developed throughout the zoarium. They are budded from a | 
central undulating axis in an annular or irregular pattern. Autozooecial 
chambers have a sub-linear shape, are eight times as long as wide, 
and diverge distally from the axis at low angles of between 10° and 
20°. They bend slightly at the exozone and vestibules are orientated |) 
at a high angle to the zoarial surface. In cross-section chambers are 
sub-rounded in shape. Endozonal walls are thin, undulatory, and | 
retain a constant width along their length. Chamber walls are © 
thickened in the exozone to a maximum width of 0.52 mm. The ) 
exozone averages 0.07 mm in width and is approximately one sixth 
of the branch diameter on either margin. 
Metapores are developed at the top of the endozone and the base |) 
of the exozone. They are small, circular to oval structures, usually , 
closed at the zoarial surface. One or two are disposed between |) 
autozooecia. 
Autozooecial apertures are moderate in size, oval in shape, widely | 
spaced approximately four to five diameters apart, and are arranged :| 
in longitudinal rows around branches. On most zoaria apertures are | 
more abundant on one side of branches than on the other. 
Acanthostyles are common. Six to ten surround autozooecial | 
apertures, often resembling a peristome, and they also occur ran- | 
domly and widely scattered in interapertural areas. They develop i) 
from the base of the exozone only. Strong longitudinal ridges also) 
decorate interapertural areas. 
DISCUSSION. Clausotrypa ramosa was first described as Sulcor-)) 
etepora? ramosa by Owen (1973: 305). He suggested that the taxon | 
is either a sulcoreteporid or arhabdomesonid depending on which of 
Owen), or the ramose zoarial form, is considered to be of stronger) 
generic importance. He assigned the taxon to the former, but ignored 
the diagnostic features of the genus Sulcoretepora, namely the 
bifoliate zoarial habit and the arrangement of autozooecia in longi- 
tudinal rows, budded from a plicated median carina. 
Several Claustotrypa species have been previously described. Of 
| 
Figs 37-40 Clausotrypa ramosa (Owen, 1973) comb. nov.; 37-39; 
Upper part of the Glencar Limestone (Viséan, Asbian), Carrick Lough, 
County Fermanagh. 37, BMNH PD9627; 37a, dendroid zoarium 
showing aborted lateral branch development, oval-shaped autozooecial 
apertures arranged in crude longitudinal rows, with striated ridged 
interapertural areas, x25; 37b, detail of 37a, showing oval-shaped 
autozooecial aperture surrounded by seven large acanthostyles. 
Acanthostyles are also developed in interapertural areas, x200. 38, 
BMNH PD9636, longitudinal section showing sublinear autozooecial 
chambers, budded from a poorly defined axis. Circular metapores are 
present at the endozone/exozone boundary, x25. 39, BMNH PD9637, 
transverse section showing pyriform autozooecial chamber cross- 
sections, circular/polygonal metapores, and acanthostyles in exozone, 
x25. 40, Limestone and Shales below Rossmore Mudstone (Upper 
Viséan), Tullaghoge, County Tyrone; Owen Collection. BELUM K.183¢ 
(lectotype); 40a, transverse section showing pyriform autozooecial 
chamber cross-sections, and circular/polygonal metapores (figured as 
Sulcoretepora ramosa by Owen, 1973, pl. 9c, x25); 40b, longitudinal 
section showing autozooecial chambers budded from an irregular axis, 
and small circular/polygonal metapores developed at the base of the thi! 
exozone region (figured as Sulcoretepora ramosa by Owen, 1973, pl. 
9b, x25). 
