Mikrofossilien aus dem Vaginatenkalk von Hälludden, Öland

Abstract:
The present paper reports about microfossils found in the Vaginatum-Limestone, Kunda-Stage, of Hälludden, Öland. The different groups observed are listed in the contents on p. 181.

The graptolites which had been treated in a representative way by O. M. B. Bulman, 1936, yielded but little news: The presence of the genus Epigraptus (E. bidens?) was proven by a thecal tongue; the ventral rim of the thecae of Didymograptus gracilis showed an indentation serving perhaps for a lophophor-like organ.

The annelids were represented mostly by dental ridges of the genera Xanioprion, Anisocerasites and Marleneites.

The hydrozoans yielded 3 genera with 3 species. Here a neotype was established for Cylindrotheca profunda, a species described 1934.

The chitinozoans, represented by 5 genera and 11 species, and the acritarchs, represented by 8 genera and about 20 species, are frequent and well preserved. Two new species are described: Leiotiolita prismatica and Ballisphaeridium tenuibarbatum.

The general part deals with fissures in acritarch shells caused by tension or pressure and often taken for “excystment openings,” with plugs reaching into the interior of the shell and probably caused by parasites, with breeding cells, pylomes and double pylomes, and with symbionts. In addition, some problematical fossils are discussed.