Sphyraena pingstiis Gunther is a common barracuda of southern Japan. It attains about 350 mm in total length when full grown. The spawning season seemed to extend from the middle of June to the middle of July, 1956, in the vicinity of Yukuhashi City, Kyushu. The authors operated artificial insemination of this fish on June 27, 1956, at Minoshima, Yukuhashi City, Kyushu, and observed the egg development and hatched larvae. The egg is pelagic, spherical in shape, measuring 0.69-0.82 mm in diameter. The yolk is colorless, transparent and very clear alveolar structure was observed in life, with a single oil-globule, colorless or very pale dull yellow, measuring 0.18-0.21 mm in diameter. The fundamental process of embryonic development is much the same with other teleostean eggs (Plate 16, Figs. 1-8). The hatching took place in about 24-30 hours after insemination, at the water temperature 21.3-26.0 ℃, when the embryonic development was as the Fig. 8. The newly hatched larva (Figs. 9-10) is 1.75 mm in length from anterior edge of yolk sac to end of caudal fin, with a oil-globule situated in the anterior part of large ovoid yolk sac. The myotome number is 14+13=27 (vertebral number of this fish is 12+12=24). The melanophores are abundant along the dorsal base, and form a triangular pattern on the neck, leaving the area above the hind brain free from pigment. The larvae in glass jars were hanging under water surface on their backs. The triangular pattern on the neck broke up in 24 hours after hatching. Small pectoral fins were formed in 39 hours. In 45 hours (Fig. 12), the yolk was reduced to a globular mass smaller than the head, the snout slightly projected, and the subdermal space developed most extensively along the bases of dorsal and anal membranous fin. The melanophores became scarce on the head and dorsal surface of trunk, but abundant on the gut. Yellowish blotches were found on the head and body. In 50 hours, the mouth opened. In 66 hours, the eyes were lightly pigmented, the air bladder became visible, and the filaments of sensory organs were found on the head (2 pairs) and body sides (4 pairs). In 72-79 hours, at the water temperature 22.2-28.5'C, the larvae attained 2.52-2.72 mm in total length, entirely consuming the yolk.

アカカマス Sphyraena pinguis Gunther は東京附近から南日本にかけて分布し全長350mmに達するカマス科Sphyraenidaeの魚である. カマス科の魚の卵発生及び稚仔魚についてはOrton(1955)がカリフォルニヤ沿岸の Sphyraena argentea Girard について発表しているが, 我国近海の魚については殆ど知られていない様である. 筆者等は1956年6月中・下旬, 福岡県行橋市蓑島において, 桝網で獲れた直後のアカカマスを用いて人工授精を行い, その卵発生と仔魚前期について観察したので報告する.