. Bulletin of the British Museum (Natural History). 68 M. G. LOCKLEY & A. WILLIAMS Discussion. Although Christiania is well known in the Ordovician successions of Scotland, Ireland and North America (Hall & Clarke 1892, Cooper 1956, Williams 1962, Mitchell 1977) and parts of Europe (Spjeldnaes 1957, Havlicek 1967), until recently (Cocks 1978: 123, 203; Hurst 1979) the genus was unknown from Caradoc and older rocks in the Anglo- Welsh Figs 232-240 Chnsiiania eliisa sp. nov. Fig. 232, holotype BB 92451, internal mould of a pedicle valve x6; Fig. 233, BB 92456, internal mould of
. Bulletin of the British Museum (Natural History). 68 M. G. LOCKLEY & A. WILLIAMS Discussion. Although Christiania is well known in the Ordovician successions of Scotland, Ireland and North America (Hall & Clarke 1892, Cooper 1956, Williams 1962, Mitchell 1977) and parts of Europe (Spjeldnaes 1957, Havlicek 1967), until recently (Cocks 1978: 123, 203; Hurst 1979) the genus was unknown from Caradoc and older rocks in the Anglo- Welsh Figs 232-240 Chnsiiania eliisa sp. nov. Fig. 232, holotype BB 92451, internal mould of a pedicle valve x6; Fig. 233, BB 92456, internal mould of a brachial valve x 6; Fig. 234, BB 92457, internal mould of a brachial valve x 6; Figs 235a, b. BB 92449, latex cast x 8 and internal mould X 4 of a pedicle valve; Figs, 236a, b, BB 92447. latex cast and internal mould of a pedicle valve, both x8; Figs 237-240, BB 94246, 92446, 92455 and 92452 respectively, internal moulds of pedicle valves x6, x4, x4 and x6 respectively; all from Llanvirn sandstones, Howey Brook, Llandrindod. Figs 233-240 are all paratypes. The specimens described here are representative of a distinctive specific stock within the genus and constitute the first record of Christiania in the pre-Ashgill successions of Wales. C. elusa sp. nov. differs from the penecontemporaneous C. oblonga Pander from Norway and Russia (Spjeldnaes 1957: 113-127) in having neither a continuous 'branchial loop' nor diagonal septa arising forward of the cardinal process (1957: fig. 27a). Indeed the new species is more reminiscent of the younger C holiedahli Spjeldnaes with its 'branchial loop' which is discontinuous near the anterolateral commissure and its transversely disposed, curved diagonal septa and fine median septum. Similarly C. elusa differs from known Scoto- Irish species, C. hilobata Reed, C. perrugata (Reed), C. porilocki Mitchell, C. sulcata Williams and C. temticincta (M'Coy), in numerous respects particularly its transverse out- line and fine dorsal septa. I. Pl
Size: 1903px × 1314px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalhistory, bookcentury1900, bookcoll
