Numerous bottom samples collected during 1971-1977 from the western half of the Beaufort Sea contained four species of myodocopid ostracodes, three new. The new species are described and illustrated, and a supplementary description is presented of Philomedes brenda (Baird, 1850) based on the specimens from the Beaufort Sea. The most abundant species is P. brenda, which is circumpolar. The new species are endemic to the Beaufort Sea. Of these Scleroconcha ruffi is common, and the remaining two are extremely rare (Empoulsenia monothrix and Bathyleberis thrix). Samples were collected at depths of 25-4200 m, but myodocopid ostracodes were not present deeper than 1926 m. Relative abundances of P. brenda and S. ruffi differed in August of the adjacent years 1976, 1977, at depths of 50-100 m, but not at depths of 25-40 m. Samples collected during October 1975, March, May, August, November 1976, and August 1977, suggest that P. brenda may be more abundant during March and May. Whether stations were with or without an ice cover seemed to have little effect on ostracode abundance. Females of both P. brenda and S. ruffi appear to bear eggs year-round. Species and genera between depths of 0-200 m (continental shelf and part of upper slope) in the Arctic and Antarctic are compared: Five of seven genera on the Arctic shelf also live on the Antarctic shelf (Simpson Index 71.4), but with no species in common. A hydrozoan colonizes the carapaces of some adult and ovigerous females of Philomedes brenda.Four other taxonomic actions not directly pertinent to this study are taken: Philomedes globosa digitiformis Chavtur, 1983, is raised to species rank as Philomedes digitiformis Chavtur; Asterope abyssicola Sars, 1869, is recombined as Prionotoleberis abyssicola (Sars), Asterope norvegica Sars, 1869, is recombined as Prionotoleberis norvegica (Sars), and Philomedes kadjakiensis Chavtur, 1893, is referred to Philomedes species inquirenda.
