LOWER CARBONIFEROUS BRYOZOA 
147 
Figs 60,61 Leioclema indentata sp. noy.; 60, Upper part of the Glencar Limestone (Viséan, Asbian), Carrick Lough, County Fermanagh; BMNH PD9621 
| (holotype); 60a, ramose colony with circular autozooecial apertures arranged in crude longitudinal rows, surrounded by large acanthostyles, with ridged 
interapertural areas, x15; 60b, detail of 60a, showing oval-shaped autozooecial apertures surrounded by six to eight large acanthostyles; smaller 
very thick exozone region, x30; 61, base of reef, Lower Carboniferous (Viséan, Asbian), Shanvaus Cross, County Leitrim, TCD.28152; 61a, ramose 
| acanthostyles are developed in interapertural areas, x85; 60c, cross-sectional view showing central axial region of thin walled autozooecial chambers and 
. 
colony., x20; 61b, detail of 61a showing small circular mesozooecial apertures between autozooecial apertures, x100. 
| Autozooecia are developed throughout the zoarium. The exact 
shape of the zooecial chambers is unknown. It appears that the cham- 
bers diverge from the centre of the branch at a low angle of 25° to 30°. 
Zooecia bend through 50° at the endozone/exozone boundary so that 
vestibules are orientated perpendicular to the zoarial surface. Cham- 
ber walls are thin (0.01—0.02 mm) in the endozone and thicken rapidly 
at the exozone which reaches a maximum thickness of 1.10 mm.Thin 
diaphragms are common at the base of the vestibule. In cross-section 
chambers are circular, pentagonal or polygonal in shape. 
1 
ig.62 Leioclema indentata sp. nov. Line drawing of external features of 
_ | BMNH PD9621; a, colony form, scale bar = 1 mm; b, Detail of surface 
| features, scale bar = 0.1 mm. 
Mesozooecia are common in the exozone, where they are dis- 
posed in three to five irregular rows between autozooecial chambers, 
but are not present in the endozone. They are circular, polygonal or 
irregular in shape, 0.03 to 0.11 mm in diameter, thin walled, hollow, 
and closed to the surface. No internal diaphragms were observed, 
perhaps due to the nature of the preservation. 
Autozooecial apertures are oval in shape, moderately large 0.12 to 
0.20 mm in diameter, and fairly regularly spaced one to two diam- 
eters apart. They are arranged in 16 to 20 poorly defined longitudinal 
rows. Each aperture is surrounded by six to seven large acanthostyles 
(0.05 to 0.08 mm in width and up to 0.1 mm in length), which indent 
the aperture margin. 
Smaller ramdomly orientated acanthostyles, and thin wavy longi- 
tudinal grooves are found in interapertural areas which are slightly 
Table 21 Measurements of Leioclema indentata (in mm). N=6. 
NM x Mn Mx CVw CVb 
ZD 61 1.66 i315) DAB! 6.92 7.38 
AD 60 0.15 0.12 0.20 9.40 9.88 
IWT 60 0.18 0.06 0.26 17.33 9.22 
Zi 60 6.23 4 8 10.48 11.11 
Z2 60 3.60 3) 5 13.48 9.11 
ET 9 0.84 0.68 1.10 2.69 S1117/ 
TE 18 0.38 0.28 0.51 8.89 6.68 
