The osphradium is an olfactory organ in certain molluscs, linked with the respiration organ. The main function of this organ is thought to be to test incoming water for silt and possible food particles.
It is a popular idea among malacologists that the presence of an osphradium should be a molluscan synapomorphy. However, a truly homologous "osphradium" is yet to be found in some groups, such as in Lepidopleuridan chitons (Polyplacophora).
- Hulbert G. C. E. B. & Yonge C. M. (1937). "A Possible Function of the Osphradium in the Gastropoda". Nature 139: 840-841. doi:10.1038/139840b0.
- Brown A. C. & Noble R. G. (1960). "Function of the Osphradium in Bullia (Gastropoda)". Nature 188: 1045-1045. doi:10.1038/1881045a0.