Inarticulate brachiopod larvae belonging to the families Discinidae and Lingulidae were found in several plankton samples of the International Indian Ocean Expedition. Present knowledge is insufficient to determine whether the discinid larvae belong to the genus Discinisca or Pelagodiscus. The lingulid larvae belong to Lingula sp. The discinid larvae were fully grown ones with pedicle and were ready to settle to a sedentary life. Most of the Lingula larvae had well developed pedicle and appeared to be old larvae unable to find suitable substratum to settle on.

The occurrence of the larvae and the stage of development of the Lingula larvae are dealt with in detail based on samples from 63 IIOE stations