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Volume 1992 (1992)
- Issue 168 Pages 1265-
- Issue 167 Pages 1165-
- Issue 166 Pages 1097-
- Issue 165 Pages 1009-
Volume 1992, Issue 166
Displaying 1-4 of 4 articles from this issue
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BAOCHUN ZHOU, NORIYUKI IKEYA1992 Volume 1992 Issue 166 Pages 1097-1115
Published: June 30, 1992
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSA total of 545 specimens belonging to the genus Krithe were obtained from 45 surface sediment samples collected from Suruga Bay, the Pacific side of central Japan. These specimens were classified into three species on the basis of differences in carapace morphology, which can be clearly traced in each species to the young larval stage (A-6). The three species were identified as K. sawanensis Hanai, 1959, K. antisawanensis Ishizaki, 1966 and K. surugensis Zhou and Ikeya n. sp. Each species has a distinct depth range and distributional area in Suruga Bay. Krithe sawanensis is distributed throughout the entire bay at depths of 120-1, 350 m. In contrast, the distribution of K. antisawanensis is restricted to the vicinity of the bay mouth, and K. surugensis is limited to the eastern area of the central trough. These two species are distributed at depths between approximately 150-650 m. The difference in distribution pattern and the intraspecific variation of the three species is correlated with environmental parameters such as water depth, water temperature, and dissolved oxygen. Two populations of K. sawanensis having distinct carapace size and vestibule shape were recognized. The populations are separated from each other by an ostracode-barren zone (OBZ) at depths of about 650-810m.View full abstractDownload PDF (2204K) -
YASUSHI YOSHIDA, YUJI OKIMURA1992 Volume 1992 Issue 166 Pages 1116-1143
Published: June 30, 1992
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSThe Omi Limestone Group belonging to the Akiyoshi Terrane yields abundantly rugose coralline fossils of the genus Amygdalophylloides from its lower part. The assemblage of Amygdalophylloides obtained from the Fukugakuchi area where the lower sequence of the Omi Limestone Group is typically developed, comprises more than 10 forms, from which the following eight species, including five new species and two unidentified species, are herein described and illustrated : Amygdalophylloides densus, sp. nov., A. denticulatus, sp. nov., A. uzurensis (Yamagiwa and Ota), A. omiensis, sp. nov., A. longiseptatus, sp. nov., A. parvus, sp. nov., A. sp. A and A. sp. B. This coralline assemblage is of Namurian A to Namurian B, Serpukhovian to early early Bashkirian age, except for the occurrence of Amygdalophylloides sp. A referred to the late Visean age.View full abstractDownload PDF (5966K) -
TATSURO MATSUMOTO, TAKEMI TAKAHASHI1992 Volume 1992 Issue 166 Pages 1144-1156
Published: June 30, 1992
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSWe have recently investigated the hitherto unexplored outcrops of Lower Cenomanian sandy rocks not far from the type section of the Mikasa Formation along the River Ikushunbetsu of central Hokkaido. Although bivalves predominate there, at least ten ammonite species are identified. In this paper the following four species are described, since they have not yet been recorded in Hokkaido : Acompsoceras renevieri (Sharpe), Utaturiceras vicinale (Stoliczka), Mantelliceras aff. Japonicum Matsumoto, Muramoto & Takahashi and Mantelliceras saxbii (Sharpe). Also a biostratigraphic correlation with the type section is attempted with a suggestion that the Acompsoceras-bearing bed may represent, though locally and with lateral change of facies, the next higher level than the Zone of Mantelliceras japonicum in the type section of the lower Cenomanian in the Ikushunbetsu Valley.View full abstractDownload PDF (2839K) -
YASUNARI SHIGETA1992 Volume 1992 Issue 166 Pages 1157-1163
Published: June 30, 1992
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSA tetragonitid ammonite, Pseudophyllites indra (Forbes) is described based on material from the Orannai Formation in the Soya area of northern Hokkaido and from the Krasnoyarka Formation in the Naiba area of south Sakhalin. P. indra, occurring in the Schlueterella kawadai Subzone of the Metaplacenticeras subtilistriatum Zone, which corresponds to the upper Campanian, has a nearly circular initial chamber in median section, a subellipsoid caecum with weakly constricted base and a ventrally located siphuncle. In various areas of the North Pacific region, the present species first appeared almost synchronously in the upper Campanian. From Santonian to early Campanian times, P. indra was distributed in the Indian region. This evidence shows that this species extended its geographical distribution from the Indian region to the North Pacific region in late Campanian time.View full abstractDownload PDF (2185K)
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