Giard (1893) described Caobangia billeti, a freshwater sabellid polychaete, based on material collected in what is now northern North Vietnam. Up to the present time it had not been re-collected and Giard's observations that it is hermaphroditic, that its eggs undergo internal development, and that, rather than having a posterior terminal anal opening, the anus opens far forward, have been questioned from time to time.

Recently collected material, as well as older material in the collections of the Division of Molluscs, Museum of Natural History, Smithsonian Institution, has allowed the confirmation ofGiard's findings and the observation of the burrows of Caobangia in 22 species of molluscs from fast-moving streams in Ceylon, northern India, Assam, Burma, Thailand, Laos, Java, Sabah, and various of the Philippine Islands.

Burrowing in snail shells appears to take place subsequent to larval metamorphosis as youngindividuals grow posteriorly from a capsule-like structure through the periostracum and into the calcium carbonate of the snail shell. There appears to be no differentiated area of the worm which can be implicated as the site of acidic secretions, and the setae of the worms seem not to be unusually worn, as would be the case if they were used to wear away the shell material.