The authors received two industrially important strains of Asp. niger group, NRRL No. 330 and No. 337, from Professor K. B. RAPER. The general impressions of those strains seemed to be very near to those of Kuro-koji-molds⁽¹⁾ (see Table 1), the black Aspergilli, which are widely used for manufacturing a kind of distilled wine from sweet potatoes in the southern districts of Japan. As for the morphological characteristics of those Kuro-koji-mold distinguished from the ordinary Asp. niger VAN TIEGHEM strains, the authors have already⁽²⁾ pointed out that the conidial surfaces are rather smooth, rough or very rarely somewhat echinulate through the optical microscope while the latter when mature are conspicuously echinulate which were expressed as colored bars according to THOM and RAPER⁽³⁾.<br> As it is shown in the electron microscopic figures 1, 2 and 3, the surfaces of the conidial walls of NRRL No. 337 and No. 330 have so-called typical rough appearance while those of Asp. niger 2126 are provided with distinct processes, ranging from 0.7 to 1.0 in length. As for the conidial wall of Asp. niger, THOM and RAPER⁽⁴⁾ described that “rough or spinulose from coloring substance deposited as tubercles, bar or loops between the outer primary wall and the inner or secondary wall” But in the present electron micrographs (see Fig. 3) these processes are not able to attribute to the colored loops at least.<br> According to the classification proposed by the authors(5) the strain NRRL No. 337 may be classified as Asp. aureus var. brevius NAKAZAWA et al.⁽⁶⁾ from the follwing morphological characteristics (see also page 524) ; i. e. the conidial surface almost smooth through the optical microscope, the primary sterigmata under 10μ in length, the conidial heads small and blackish brown shade in color, the conidiophores short, andE the nitrite assimilation test positive (see page 524). Secondly the strain NRRL No. 330 may be classified as Asp. saitoi var. kagoshimaensis SAKAGUCHI et al.⁽⁷⁾ from l the following morphological characteristics (see also page 524); i. e. the conidial surface almost smooth through the optical microscope, short sterigmata about 10μ in length.<br> Amylase producing abilities of “Asp. niger” NRRL 330, 337 and Asp. oryzae NRRL 692 were compared with several strains of Japanese potent amylase producers. Whgn cultivated on wheat bran, both “Asp. niger” NRRL 330 and 337 produce the amylase system of Asp. usamii type⁽⁸⁾ and their activities are 6/7 and 1/2, respectively, of that of Asp. usamii R-0635. Amylase system of Asp. oryzae NRRL 692 belongs to “Asp. oryzae type” and its activity is about 7/10 of that of Asp. oryzae S-7⁽⁹⁾ and about 1.4 times higher than those of Asp. oryzae M 2-1 or S 1-1.