摘要
日本刺沙蚕Neanthes iaponica(Izuka)分布于我国黄海、渤海沿岸；日本的日本海和太平洋沿岸．为中国和日本的特有种。
This report is part of the study on the morphology and the larval development of species of the family Nereidae found in the China Sea.Neanthes japonica ( Izuka ) is a specific species in China and Japan. It is usually most abundant in sandy-mud sediments and estuaries of the Bohai ( Dalian, Peidaiho, Tiensien, Yentai), the Yellow Sea( Qingtao, Weihai and the Yangtze River ( Shanghai ).Neanthes japonica and N. diversicolor are very similar in morphology, but they are different in reproduction. During the spawning season, N. japonica was found in the marine regiments. They were collected on 15 th March, 1963, at tempersture of 8 -10％ in the sea water of Qingtao.The larvae developed slowly and settled as the 2lst day with seven -setiger nectochacte. Settlement and metamorphosis occured in a relatively short period of time because only 3 days metamorphosed from seven setiger-nectochaete to ten-setiger juvenile.The sequence of the early embryology and larval development in summarized as follow:
