nereidiformia

\\ˌnirēˌidəˈfȯrmēə, nə̇ˌrēəd-\ noun plural

Usage: capitalized

Etymology: New Latin, from Nereid-, Nereis, genus of polychaete worms + -iformia (from Latin, neuter plural of -iformis -iform)

in some classifications : a division of polychaete worms nearly equivalent to Errantia