The genus Echinarachnius, or sand-doller, of Japan comprises three forms: E. vzirabilis (A. AGAssIZ), E. griseus MORTENSEaNn,d E. parma var. obesus H. L. CLARK. The first and the second are common forms along the Japanese coasts, while the third has hitherto been known only from SakhaIin. I could recently make a fair collection of sea-urchins mostly from southern Japan, and a review of this genus is given in the foregoing Japanese text. The chief result arrived at by me is a correction of MORTENSENv'Sie w on E. griseus as stated below. Those marked with an asterisk are new localities added by me. 1. E. mirabilis. This is a species peculiar to Japan and the commonest of the three. Localities: Otaru, Ilakodate, Mutsu-Wan, Obama (Fukui-Ken), Tokyo, Yokohama, Nai-Wan (Chiba-Ken), Kanagawa, Misaki, Sami (Okayama-Ken), Tomo, Tsuyasaki, Genkai-Jima (Fukuoka-Ken), Hakata-Wan, Omura, Amakusa. 2. E. griseus. This form is also indigenus to Japan and is a species established by MORTENSEinN 1927. In regard to the position of the periproct as one of the most important features of this species, MORTENSEN said " the anal opening is distinctly supramarginal." His specimens were from Yamagata-Ken and the largest among them was 50 mm long, so far as I can learn. Among my specimens from Shibushi (Kagoshima-Ken) those up to 50 mm in length show clearly the supramarginal position of the periproct, as MORTENSEN not iced. But, in all the larger specimens, 57-62 mm long, the position is quite marginal. This fact leads me to think that the specimens examined by MORTENSEN are probably those which were still in a young stage. It seems safe to conclude that the anal opening assumes the marginal position when the sand-dollar reaches the older stage than MORTENSEN'S. In other words, in this species also the migration of the periproct from supramarginal position to marginal takes place as it does in other two forms, only very late in age. Localities: Muroran, Mutsu-Wan, Yamagata-Ken, Kitasaki (Fukuoka-Ken), Shibushi. 3. E. parma var. obesus. This is a variety having a very wide range of distribution along the Asiatic coasts. I give Akkeshi-Wan, Hokkaido, as a new locality in addition to Sakhalin which has long been known as the sole habitat in Japan. Localities in Japan : Sakhalin, Akkeshi-Wan.