1. The seasonal evolution of the gonads of A. chiajei during the period from April 1965 until March 1966 has been described. The reproductive cycle allows a period of sexual rest at the end of autumn, a period of growth in winter, a period of maturity in spring and in summer, and an egg-shedding period from the end of summer until the middle of autumn.2. The seasonal cycle of planktonic larva was studied during a period of three years. The larvae appear in autumn; however, a few of them were caught in spring and in summer.3. The problem of maturation of the primary oocytes is discussed. The larvae described by Muller (1853), Mortensen (1920) and Chadwick (1914) are related to A. chiajei. The periods of reproduction of this species in various Northern and Mediterranean regions are specified.