UTRECHT MICROPALEONTOLOGICAL BUllETINS

teristic and Pander's drawing is very realistic. The following may be added to
Pander's description:
The whole unit is rather translucent, almost straight, or slightly bent
sidewards. The base is not high compared to the width of the cusp; its oral
edge is convex and carries a high keel. The basal cavity is shallow and slightly
convex in oral direction below the oral edge, whereas it is concave under the
basal stretch of the cusp. The aboral margin is almost straight or slightly
undulating in side view. The cusp is wide and strongly keeled. The anterior
keel is almost straight, the posterior keel is convex. If bent, the outer side of
the cusp usually is flat, whilst a carina runs to its inner side. Where the latter
meets the aboral margin there may be a weak parapet-like extension.
The suberectiform elements (= Distacodus peracutus LINDSTROM) have
a short oral edge and two prominent lateral costae (PI. 2, figs. 3a, b). These
prominent costae enable differentiation from the suberectiform elements of
Drepanoistodus inaequalis (PANDER), figured at PI. 2, fig. 8. The suberectiform
elements of Drepanoisto dus inconstans (LINDSTROM) (PI. 3, fig. 12)
are less proclined and carry less prominent costae.
Within the intraspecific form variation of the form species Oneotodus
variabilis LINDSTROM, the acodiform-, the scandodiform- and the almost
symmetrical drepanodiform elements can be recognized (see PI. 2, figs. 6, 5,
4 respectively).
Regionaloccurrence: At Kopingsklint this species occurs from the lowermost
part of member Dk 1 up to halfway member Kk 1. Near Horns Udde from
member Dh 1 up to and including part of member Kk 2.
Biostratigraphic range: Drepanoistodus acuminatus was found from the
Drepanoistodus acuminatus Assemblage Zone up to and including the
Prioniodus deltatus Assemblage Zone (fig. 15).
Drepanoistodus
conulatus (LINDSTROM), emend. VAN WAMEL, herein
(PI. 3, figs. 1-4)
Drepanodus conulatus LINDSTROM, 1955a, p. 561, PI. 2, fig. 34; PI. 4, fig. 34
Scandodus furnishi LINDSTROM, 1955a, p. 592, PI. 5, fig. 3.
Scandodus furnishi LINDSTROM, emend. LINDSTROM, 1971, p. 39.
Drepanodus cyranoicus LINDSTROM, 1955a, p. 561, PI. 5, fig. 8.
Remarks: According to the emended definition of Drepanoistodus, this
probably is another multi-element species of that genus.
The suberectiform element (see PI. 3, fig. 2) is Drepanodus cyranoicus
LINDSTROM.
The drepanodiform element is Drepanodus conulatus LINDSTROM,