1887 Amphisphaera cronos - Haeckel p.144; p1. 17, fig 5 | 1966 Xiphatractus cronos - Benson p. 182-183; pl. 7, figs. 12-13 | 1979 Stylatractus spp. - Nigrini and Moore p. S55-S56; pl. 7, figs. 1a-b | 1983 Xiphatractus cronos - Benson p. 510; pl. 4, fig. 8 | 1998 Stylatractus spp. group - Boltovskoy fig. 15.35 |
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