Abstract
In this paper is given description of Idiacanthus panamensis (female of total length 420 mm.) from a depth of 1000 m., off Kesennuma (Miyagi Pref.) by our research boat, No.1 Asahi-maru (56 ton), and chartered boat, No.10 Shinkai-maru (51.6 ton) during survey of deep-water fishing grounds (500-1000 metre depth) in bottom trawl without otter boards in Tohoku and adjacent region during July-October, 1951, and the result of measurement of the four specimens (total length 260, 134, 112 and about 84mm.) taken from the stomachs of Theragra chalcogramma (PALLAS) caught off Hachinohe in August, 1958. The specimens well agree with to the key to the species of this genus by REGAN and TREWAVAS (1930), but all body propotion has not characters of I. panamensis, but in some points have characters of I. fasiola.
According to REGAN and TREWAVAS (1930) photophores from pelvics to origin of anal number 15-18 in I. fasiola, and 16-22 in I. panamensis, but my specimens have 23-24.
Further I added the distribution records of this species in Japanese water; hitherto it is known from Kumano-nada and off Kochi.
