Placostylus, or flax snails, are a genus of very large, air-breathing land snails, terrestrial pulmonate gastropod molluscs in the family Bothriembryontidae.

[3][2] The shells of the snails in this genus can be as large as 4.5 inches (11 cm) in maximum dimension.

[4] Breure et al. (2010)[5] moved Prestonella and Bothriembryon to Placostylidae.

Subsequently, Breure & Romero (2012)[3] confirmed previous results from 2010 and they renamed Placostylidae to Bothriembryontidae.

[3] This genus of snails occurs in the Solomon Islands, Vanuatu, New Caledonia, Fiji, Lord Howe Island, and Northland in New Zealand.