UTRECHT MICROPALEONTOLOGICAL BUllETINS

Udde from member Dh 1 up to the top of member Dk 1.
Biostratigraphic range: Cordylodus rotundatus PANDER was found from the
Cordylodus rotundatus Assemblage Zone up 'to and including the. Pro topanderodus
rectus /Oelandodus costatus Assemblage Zone (fig. 15).
Genus Drepanodus PANDER, 1856, emend. LINDSTROM, 1971
Type species: Drepanodus arcuatus PANDER, 1856.
Emended definition: A multi-element genus with drepanodiform elements
and "a Scandoduslike oistodiform element" (see Lindstrom, 1971, p. 41).
Drepanodus arcuatus PANDER, 1856, emend. VAN WAMEL, herein
(PI. 1, figs. 10-13)
Drepanodus arcuatus PANDER, 1856, p. 20, PI. 1, figs. 2,4,5, 17, not 30, 31. LINDSTROM, 1955a,
p. 558, PI. 2, figs. 30-33; Fig. 3].
Drepanodus arcuatus PANDER, emend. LINDSTROM, 1971, p. 41, figs. 4, 8.
Drepanodus cf arcuatus PANDER. LINDSTROM, 1955a, p. 560, PI. 2, figs. 45, 46; Fig. 4c.
Drepanodusflexuosus PANDER, 1856, p. 20, PI. 1, figs. 6-8.
Drepanodus sculponea LINDSTROM, 1955a, p. 567, PI. 4, fig. 40; Fig. 3L.
Drepanodus? gracilis (BRANSON & MEHL, 1933). LINDSTROM, 1955a, p. 562, PI. 4, fig. 44, PI. 5,
figs. 6, 7.
Acontiodus arcuatus LINDSTROM, 1955a, p. 547, PI. 2, figs. 1-4; Fig. 3A.
Scandodus pipa LINDSTROM, 1955a, p. 593, PI. 4, figs. 38-42; Fig. 3P.
Remarks: Instead of the drepanodiform and oistodiform elements mentioned
by Lindstrom (1971, p. 41), this multi-element species is thought to
comprise four types of elements. In this paper these elements will be called
the arcuatiform element (PI. 1, fig. 10), the sculponeaform element (PI. 1,
fig. 11), the graciliform element (PI. 1, fig. 13) and the pipaform element
(PI. 1, fig. 12), after the formspecies names, which were formerly given to
these elements.
Acontiodus arcuatus is a rare variant of Drepanodus arcuatus, with two
costae running parallel beside the posterior edge. Similarity in morphology
and stratigraphic range make it highly probable, that Drepanodus sculponea
also is part of this multi-element species. Furthermore, there appear to be
transitional forms between Scandodus pipa and Drepanodus ? gracilis, all
occurring together in one sample. The graciliform element is relatively rare.
Regional occurrence: At Kopingsklint the species was found from the base
of member Kk 1 up to the top of the Horns Udde Formation. In section 6
from member Ka- d 1 up to the top of the Horns Udde Formation. Near
Horns Udde from member Kk 2 up to the top of the Horns Udde Formation.
Biostratigraphic range: This species was found from the Drepanodus arcuatus