93., Vicarya の或る標本に就て

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While TAKEYAMA classified in 1933 Japanese Vicarya into V., collosa JENKINS and V., verneuili yokoyamai TAKEYAMA, YABE and HATAI, through their precise study, lately split the former species into three subspecies, japonica, yokoyamai and martini., In TAKEYAMA's Tuyama from of V., callosa, the number of spinose tubercles is constant throughout the whorls and has two primaly spiral ridges below the band., The fact that the spinose tubercle is produced oblique to the axis of the shell renders it distinguishable from the typical from of callosa as pointed out by YABE and HATAI., Although the writer is not quite convinced of the advisability of snbspecific distinction in view of this difference, he accepts calling the form, V., callosa japonica., V., verneuili has no tubercle in its nepionic whorl but numerous granules some of which develop into spinose tubercles in the adult stage., This feature is typical of V., verneuili yokoyamai (the Tukiyosi form) and is never seen in either V., callosa or V., callosa japonica., As this ontogenetical difference is an important one, the writer cannot approve of the reference of the Tukiyosi form to V., callosa as a subspecies of the latter., A further difference may be noted in the primary spiral ridges below the subsutural band, there being two in callosa but three which are beaded in Tukiyosi., The writer procured a specimen having no spinose tubercle from the Tukiyosi bed and found that it can hardly be distinguished from V., callosa martini except that the tubercles in this specimen assume the spinose aspect in the last two or three whorls., V., callosa martini may be an intermediate form linking the spineless form with V., verneuili yokoyamai, especially as V., callosa martini is found associated with V., verneuili yokoyamai., In conclusion the main points may be noted as follows : (1) the Tuyama form of Vicarya is identical with V., callosa japonica YABE and HATAI (2) the Tukiyosi form of Vicarya may be identified with V., verneuili yokoyamai TAKEYAMA but may not be taken as a subspecies of V., callosa (3) V., callosa japonica and V., verneuili yokoyamai may not be regarded as local variations within an identical species (4) V., callosa martini YABE and HATAI may be a variant form of V., verneuili yokoyamai (5) TAKEYAMA's view that V., callosa japonica indicates the Lower Miocene Oigawa stage and V., verneuili yokoyamai, the Middle Miocene Togari stage is justifiable.,
日本地質学会の論文
1939-10-20

著者

池辺展生
大阪市大・理

93., Vicarya の或る標本に就て

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