P.N. WYSE JACKSON 
DISTRIBUTION. Ireland, England, Belgium, and the CIS (former 
Soviet Union). 
Pseudonematopora planatus sp. nov. Figs 3c, 10-15 | 
t 
HOLOTYPE. BMNH PD9450; Upper part of the Glencar Lime- | 
stone (Viséan, Asbian), Carrick Lough, County Fermanagh. 
PARATYPES. BMNH PD9451-9472, 9741; TCD.34018-34025, 
34137, 34160, 34161, 42561, 42607; BELUM K2222; all from) 
same locality and horizon as above. TCD.42516-42519, Upper part | 
of the Glencar Limestone (Viséan, Asbian), Sillees River, County 
Fermanagh | 
DERIVATION OF TRIVIAL NAME. From the Latin planus meaning 
plain and unornamented. | 
DIAGNOSIS. Pseudonematopora with slender dendroid noon 
Branches dichotomise infrequently and at a high angle. They are’ 
circular to sub-circular in cross-section and are a constant width’ 
throughout their length. Autozooecial apertures occur in 6 to 8) 
longitudinal rows. They are circular in shape and have an arcuate, 
proximally located, peristomial rim. A faint longitudinal ridge oc- 
curs in the smooth interapertural area. Autozooecial budding is/ 
annular from a central axis. Chambers diverge at a low angle in the) 
endozone before bending in the exozone to become orientated at an’ 
angle of 60° to 70° to the zoarial surface. Zooecial walls are thin ini 
the endozone and do not thicken in the exozone. Terminal dia~ 
phragms may be developed. Skeletal cysts are lacking. | 
DESCRIPTION. Colonies are small, delicate and have irregularly 
dichotomising straight branches, which are circular in cross-section 
and undulatory in outline. The largest fragment examined is 13.2 
mm in length. On no specimen were two dichotomies seen. 
Autozooecia occur in 6 to 8 longitudinal rows around the circum 
ference of the zoarium except for a thin barren area on the reverse 
They are budded from a distinct central axis in an annular pattern) 
Zooecial chambers diverge from the median wall at an angle of 10° 
to 15° in the endozone. The exozone is reached when the chambery 
bend fairly abruptly through 60° to 70°. The living chambers art 
orientated nearly perpendicular to the zoarial surface. The complet 
chamber is nearly four times as long as it is wide. Interzooecial wall 
are very thin in the endozone but thicken considerably in thy 
exozone. Basal diaphragms are not developed and the zooecia 
chambers are simple tubular structures. 
Interapertural areas are smooth with a single faint longitudine 
Figs 10-14 Pseudonematopora planatus sp. nov. Upper part of the 
Glencar Limestone (Viséan, Asbian), Carrick Lough, County 
Fermanagh; 10, BMNH PD9450 (holotype); 10a, colony fragment | 
showing cylindrical branch shape, with circular autozooecial apertures | 
developed in irregular longitudinal rows; apertures surrounded by 
proximal peristomes that extend beyond the branch margin giving an | 
uneyen outline, x12; 10b, detail of 10a showing the smooth 
interapertural areas, x80. 11, BMNH PD9452 (paratype), reverse 
surface showing longitudinal sinuous series of small nodes, x12. 12, 
BMNH PD9470 (paratype), tangential section showing the central axia 
region with a row of autozooecial either side of it, and the marginal 
protrusion of the proximal peristmes, x35. 13, BMNH PD9471 
(paratype); 13a, longitudinal section showing thin axial region from 
which are budded autozooecial chambers and the thickened exozone, 
x20; 13b, detail of 13a showing brown bodies in autozooecial chambey 
trapped behind a thin linear terminal diaphragm (arrowed), x35. 14, 
BMNH PD9452 (paratype), transverse section showing radial 
arrangement of seven autozooecial chambers around the central axis, 
x35. 
