Abstract
Females of the oceanic squid Onychoteuthis borealiaponica OKADA, which had copulated, were investigated concerning their morphological characteristics and method of copulation, using one and two other specimens jigged in 1976 and 1979 respectively in the Pacific waters with the following results: 1. Since this species does not possess the hectocotylized arm, it is supposed that at the tiem of copulation spermatophores are implanted directly onto the ventral mantle of a female by the elongated penis of a male. 2. The specimens had cuts 60-80 mm in total length, 1-3 mm in width and 3-5 mm in depth on the mid-ventral mantle near the anterior end. A large number of spermbulbs were implanted in the muscular tissues of the mantle at the cut. It seems that the cuts were made by the beak of a copulating male. 3. It is presumed that this species sopulates at the advanced state of maturity of the female, namely, when the ovarian weight amounts to some 35-78 gr. and the color of genital organs turns orange. 4. The posterior end of an implanted spermbulb is exposed at the surface of the cut. It is supposed that the eggs spawned from the copulated female are fertilized outside the body by the sperms released from the implanted spermbulb.
