. Bulletin of the British Museum (Natural History). FARINGDON SPONGE GRAVEL BRYOZOA 123. Figs 125-127 Clausa zonifera Canu & Bassler. Fig. 125, BM(NH) D57719; 125A, growth tip, x 52; 125B, autozooecia and open kenozooecia, X 100. Fig. 126, BM(NH) D57720, autozooecia and occluded kenozooecia, x 138. Fig. 127, BM(NH) D57735, concave proximal fracture surface of a branch, x 35. sometimes concave (Fig. 127), breakage apparently occurring at a position of weakness, possibly a growth check. Ill-defined maculae are usually developed and consist of bands, aligned transverse to growth dir
. Bulletin of the British Museum (Natural History). FARINGDON SPONGE GRAVEL BRYOZOA 123. Figs 125-127 Clausa zonifera Canu & Bassler. Fig. 125, BM(NH) D57719; 125A, growth tip, x 52; 125B, autozooecia and open kenozooecia, X 100. Fig. 126, BM(NH) D57720, autozooecia and occluded kenozooecia, x 138. Fig. 127, BM(NH) D57735, concave proximal fracture surface of a branch, x 35. sometimes concave (Fig. 127), breakage apparently occurring at a position of weakness, possibly a growth check. Ill-defined maculae are usually developed and consist of bands, aligned transverse to growth direction, which are rich in kenozooecia. Autozooecia have open, circular apertures, lack frontal walls, and are surrounded by kenozooecia (Figs 125B, 126). Kenozooecia have smaller, more variably-sized apertures than autozooecia. Occlusion of kenozooecial apertures is common (Fig. 126); occluded apertures appear polygonal whereas open apertures appear rounded. Terminal diaphragms are apparently pscudoporous and arc situated slightly below the level of the aperture so that the interzooecial walls stand out as low ridges. Brood chambers arc unknown. In section, zooccial walls arc indistinctly laminated and relatively thick in the cndozone. Diaphragms other than terminal diaphragms have not been observed. Kenozooecia arc seen to bud in the exozonc which is poorly differentiated from the endozone. Measuremeni-S. TAM, ()â KM)-14 mm; KAM, ()-()2 () (H) mm. Remarks. This species is very common at Faringdoii hut has not been recorded elsewhere. It is mosX likc!\ to be conluscii with Tetrocycloecia multiporosa which shares with Clausa zonifera a similar arrangement of autozooecia and keno- zooecia in the dendroid colony branches. However, there are several points of distinction including: the larger size of colony branches and autozooccial apertures in C. zonifera: the slight autozooecial peristomes and typically funnel- shaped kenozooecia in T. multiporosa; and the occurrence of maculae
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