Recently, many corals were collected by the writers from the Imaura Group in the eastern part of the Shima Peninsula. This Group geotectonically belongs to the southern subbelt of the Chichibu belt. It is bounded on the north by the Middle to Upper Permian Aonomine Group and on the south by the Tsuiji Group probably correlated with the Konose Group in Kyushu. These Groups are in contact with each other by faults.
The Imaura Group (10220 m+thick) trends ENE-WSW and dips northward of about 5060 degrees ; mainly composed of sandstone, mudstone and alternations of sandstone & mudstone, occasionally intercalating grey limestone lenses.
The limestone lenses in the Imaura Group yield 46 coral species including 9 new species as shown in Table 2. The coral assemblage listed in Table 2 is very similar to those of the Upper Jurassic in the outer zone of Southwest Japan, Kwanto massif and Soma area. This datum does not conflict with the evidence from the Torinosu type pelecypod assemblage in this Group.

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