Original Papers
New species of the genus Douvilleiceras (ammonoid) from the Lower Cretaceous Yezo Group in Hokkaido
2003 年 79B 巻 8 号 p. 237-241
詳細
2003 年 79B 巻 8 号 p. 237-241
Two new species of douvilleiceratid ammonite, Douvilleiceras compressum and D. kawashitai, are described from the Lower Cretaceous Yezo Group in the Pombetsu Valley of Hokkaido. D. compressum is unique in its compressed whorl section in the genus. D. kawashitai is fairly similar to D. orbignyi Hyatt in its morphological characters, but the former is distinctly characterized by six rows of tubercles, instead of seven for the latter, on each side of the whorl.
(Communicated by Tatsuro MATSUMOTO, M. J. A., Oct. 14, 2003)
