. Bulletin of the British Museum (Natural History). 86 PITT AND TA^XOR does not occupy the area of substratum between branches in the manner of Reptoclausa (see p. 82). In the absence of gynozooecia, assignment to Idmonea must be provisional. Gynozooecia in the type species of Idmonea {I. triquetra Lamouroux) are longitudinally elongate. Canu & Bassler's holotype of /. denticulata is a poor specimen in which the 'denticulated peristomes' are apparently a result of growth of diagenetic calcite crystals. The keno- zooecial selvedge of /. alipes Gregory, 1899, with which Canu &
. Bulletin of the British Museum (Natural History). 86 PITT AND TA^XOR does not occupy the area of substratum between branches in the manner of Reptoclausa (see p. 82). In the absence of gynozooecia, assignment to Idmonea must be provisional. Gynozooecia in the type species of Idmonea {I. triquetra Lamouroux) are longitudinally elongate. Canu & Bassler's holotype of /. denticulata is a poor specimen in which the 'denticulated peristomes' are apparently a result of growth of diagenetic calcite crystals. The keno- zooecial selvedge of /. alipes Gregory, 1899, with which Canu & Bassler compared their new species, is much broader than that of /. denticulata. I. triquetra, from the Middle Jurassic, differs in having branches which bifurcate more regularly and autozooecia with slightly raised margins to their subhexagonal frontal walls. This is a relatively rare species at Faringdon where it is found encrusting oyster shells and pebbles. It is recognizable by the rather straggly, seldom-dividing branches. Idmonea radiolitorum d'Orbigny, 1850 Figs 36-37 1850 Idmonea radiolitorum d'Orbigny: 200. 1851 Proboscina radiolitorum (d'Orbigny) d'Orbigny: 854; pi. 633, figs 8-10. 71853 Proboscina ricordeauana d'Orbigny: 850; pi. 759, figs 6-7. 1899 Proboscina radiolitorum (d'Orbigny); Gregory: 48; pi. 3, fig. 5. 1926 Proboscina radiolitorum (d'Orbigny); Canu & Bassler: 7; pi. 27, figs 1, 2. 1926 Proboscina zic-zac d'Orbigny; Canu & Bassler: 7; pi. 29, fig. 7. 1971 Proboscina cf. radiolitorum (d'Orbigny); Hillmer: 38; pi. 2, fig. 1. Holotype. MNHN d'Orbigny Colin 6975 (Voigt photocard 5827), Turonian, Angouleme, France. Other MATERIAL. BM(NH) D7981, Treacher Colin; D52199, D52201, Little Coxwell Pit, Pitt Colin; D55240, D55243, D55244, Little Coxwell Pit, Gaster Colin; D55241 (3), Hinde Colin; D55242, D55245, Little Coxwell Pit, Thomas Colin. Description. Zoarium adnate, consisting of round-topped, ribbon-like branches 4 or 5 zooecia across and 0-9-1-8 mm wi
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