Spicule dimensions of Siphonodictyon insidiosum (Johnson, 1899); from drawing of spicules of holotype

Substrate: upon shells of Ostrea and Chama; Sampled by 'fishermen' and identified by J. Johnson as 'Acca insidiosa'. All measurements are of mature, fully formed oxeas (from drawing). Small sample size insufficient, does not allow statistical comparison with other samples. Measurements conducted by C. Schönberg on Johnson's Fig. 1. Data are sorted vertically by spicule width.; Johnson, James Y. (1899) Notes on some sponges belonging to the Clionidae obtained at Madeira. Journal of the Royal Microscopical Society, Transactions of the Society 9: 461-463 (S. insidiosum: pp. 161-162, Fig. 1).