要　旨　埼玉県北葛飾郡庄和町の工事現場に現れた，上部更新統木下層の貝化石層から，5科6属6種，119点の十脚甲殻類化石が得られた．これらは鉗脚などの破片であり，おもにGrynaminna grandis からなる．この化石群集は浅海に堆積したもので，潮流の速い潮間帯の砂地が近くに広がっていたと考えられる．

キーワード：埼玉県庄和町，上部更新統，木下層，十脚甲殻類化石

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図3　1-12. Grynaminna grandis. 1；左大鉗脚の不動指・掌部．a，側面；b，近心面．2：右大鉗脚の不動指・掌部．a，側面；b，近心面．3：左小鉗脚の不動指．a，側面；b，近心面．4：右小鉗脚の不動指．a，側面；b，近心面．5：左大鉗脚の可動指．a，側面；b，近心面．6：右大鉗脚の可動指．a，側面；b，近心面．7-8：左小鉗脚の可動指．a，側面；b，近心面．9-10：右小鉗脚の可動指．a，側面；b，近心面．11：左大鉗脚の長節．側面．12：右小鉗脚の長節．側面．13. Diogenes cf. edwardsii　トゲツノヤドカリの近似種. 左小鉗脚の可動指．a，側面；b，近心面．14-16. Actaea semblatae　サメハダオウギガニ. 14：右鉗脚の不動指・掌部と腕節．a，側面；b，近心面．15：右鉗脚の不動指・掌部と可動指．a，側面；b，近心面．16：甲．a，背側；b，腹側．17. Philyra syndactyla　ヒラコブシ. 左小鉗脚の可動指．a，側面；b，近心面．18-20. Leucosia sp.　ツノナガコブシ. 18：左鉗脚の不動指・掌部と腕節．a，側面；b，近心面．19：左鉗脚の長節．a，側面；b，近心面．20：右鉗脚の長節．a，側面；b，近心面．21. Cyclograpsus sp.　アカイソガニ属の未定種．右鉗脚の不動指・掌部と可動指．a，側面；b，近心面．

Fig. 3. 1-12. Grynaminna grandis. 1: propodus of the left major cheliped. a, outer; b, inner view. 2: propodus of the right major cheliped. a, outer; b, inner view. 3: fixed finger of the left minor cheliped. a, outer; b, inner view. 4: fixed finger of the right minor cheliped. a, outer; b, inner view. 5: dactylus of the left major cheliped. a, outer; b, inner view. 6: dactylus of the right major cheliped a, outer; b, inner view. 7-8: dactylus of the left minor cheliped. a, outer; b, inner view. 9-10: dactylus of the right minor cheliped. a, outer; b, inner view. 11: merus of the left major cheliped. outer view. 12: merus of the right minor cheliped. outer view. 13. Diogenes cf. edwardsii. dactylus of the left minor cheliped. a, outer; b, inner view. 14-16. Actaea semblatae. 14: propodus and carapus of the right cheliped. a, outer; b, inner view. 15: dactylus and propodus of the right cheliped. a, outer; b, inner view. 16: carapase. a, dosal; b, ventral view. 17. Philyra syndactyla. dactylus of the left minor cheliped. a, outer; b, inner view. 18-20. Leucosia sp.. 18: propodus and carapus of the left chelliped. a, outer; b, inner view. 19: merus of the left cheliped. a, outer; b, inner view. 20: merus of the right cheliped. a, outer; b, inner view. 21. Cyclograpsus sp.. dactylus and propodus of the right cheliped. a, outer; b, inner view.

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Decapod Crustacea from the upper Pleistocene Kioroshi Formation
in Showa-machi, Saitama Prefecture, Central Japan.

Kiichi Obata
Saitama Museum of Natural History
Nagatoro Chichibu-gun Saitamama, 369-1305 Japan
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Yaoko Hayashi
Volunteer stuff in Saitama Museum of Natural History
Nagatoro Chichibu-gun Saitama, 369-1305 Japan

Abstract
　　Six species of decapods belonging to six genera in five families are recorded from the upper Pleistocene Kioroshi Formation which was discovered from the construction site in Showa-machi, Kitakatsushika-gun, Saitama Prefecture, Japan. The decapod fossils, which are mainly broken pieces of cheliped, consists chiefly of Grynaminna grandi. It is thought that these fossils deposited in the littoral zone, near the intertidal sandflat where the tidal current is fast.