. Bulletin of the British Museum (Natural History). FARINGDON SPONGE GRAVEL BRYOZOA 141 1984 Echinocava raulini (Michelin); Delamette & Walter: 35; pi. 5, fig. 5. 1984 Plethopora cf. aptensis Canu & Basslcr; Delamette & Walter: 35; pi. 5, fig. 7. Material. BM(NH) D52195 (3), D553()6, Little Coxwell Pit, Pitt Colin; D55103, D57727 (3 thin sections), D57949-50, Little Coxwell Pit, Thomas Colin; D553()l, Little Coxwell Pit, Elliott Colin; D57652-5, Davis Colin. USNM 69903, 5 syn- types of Plethopora aptensis Canu & Bassler, 1926. OUM , , Davey Colin. Description.
. Bulletin of the British Museum (Natural History). FARINGDON SPONGE GRAVEL BRYOZOA 141 1984 Echinocava raulini (Michelin); Delamette & Walter: 35; pi. 5, fig. 5. 1984 Plethopora cf. aptensis Canu & Basslcr; Delamette & Walter: 35; pi. 5, fig. 7. Material. BM(NH) D52195 (3), D553()6, Little Coxwell Pit, Pitt Colin; D55103, D57727 (3 thin sections), D57949-50, Little Coxwell Pit, Thomas Colin; D553()l, Little Coxwell Pit, Elliott Colin; D57652-5, Davis Colin. USNM 69903, 5 syn- types of Plethopora aptensis Canu & Bassler, 1926. OUM , , Davey Colin. Description. Zoarium of thick dendroid branches (Figs 160- 161) , occasionally bifurcating, astogenetically variable in diameter (1-5-6 mm), with blunt rounded growth tips. The autozooecia are in fascicles (Fig. 163A), about 1 mm in diameter, subcircular in outline and projecting above the general level of the colony surface as rounded mamelons; the remainder of the colony surface is covered with cancelli (Fig. 162) . Autozooecial apertures are polygonal and increase in size towards the centre of the fascicle. Outer parts of autozooecia are directed distally up the branch. Cancelli have small funnel-shaped, subcircular apertures and thick walls (Fig. 163B). Thin sections show that the autozooecia are long, slender tubes budded within branch endozones, whereas cancelli are very short tubes budded close to the branch surface within the exozone. No diaphragms have been observed. The micro-. Fig. 161 Fchinocava raidinii (Michelin), DSNM (i^JyO.^a, syntypc o[ Plethoporti apwnsis C'aiui & Hasslcr. x 22; sec also Fig. I(i2. I. structure of the zooccial wall is amorphous and cloudy in appearance without distinct lamination, but the thick walls of the kenozooecia have laminations subparallcl to the colony surface. An apparent brood chamber is present on the proximolateral side of a fascicle in BM(NH) D57949 (Fig. 163C). It is a convex swelling roofed by cancellate interior wall. A hole within t
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