Two new deep sea species of the genus Cytheropteron (C. branchium and C. pherozigzag spp. nov) are described. Both species occur in abyssal and bathyal Pliocene to Quaternary environments in the S. W. Pacific; the latter species has also been recovered from abyssal palaeodepths in the N.E. Atlantic and E. Indian Ocean in the Late Quaternary. Both species are unusual in possessing shallow yet prominent slit-like structures below and posteroventral to the alar process. Such structures are unknown in other species of the genus; their possible function is discussed.
- Received January 1, 1984.
- Revision received January 1, 1985.
- © 1986 The Micropalaeontological Society