UTRECHT MICROPALEONTOLOGICAL BUllETINS

fig. 19 Sergeeva's conodont zones are correlated with the conodont zones
proposed now. The chronostratigraphic units from which Sergeeva obtained
her conodont faunas were put in this table as well.
Sergeeva's Zone of Cordylodus angulatus is characterized by the occurrence
of Cordylodus angulatus together with Cordylodus rotundatus, Drepanodus
arcuatus and Drepanoistodus acuminatus, before the first appearance
of Paroistodus parallelus, Drepanoistodus forceps, and Drepanoistodus inconstans;
all these species except Cordylodus angulatus and Cordylodus
rotundatus being named as emended in this paper. This Zone of Cordylodus
angulatus is correlative with the rock-interval on north-western Oland, containing
our Cordylodus rotundatus up to Prioniodus deltatus Zones inclusive
(figs. 15 and 19). Part of Sergeeva's Zone of Cordylodus angulatus thus
appears to correspond to the Zone of Shumardia and the Zone of
Apatokephalus serratus as described by Tjernvik (1956) from Kopingsklint
(see fig. 19).
Sergeeva's Subzone of Drepanodus proteus seems to be characterized by
the concurrence of the ranges of our Paroistodus parallelus, Drepanodus
arcuatus, Drepanoistodus forceps and Drepanoistodus inconstans. Thus
defined, the Subzone of Drepanodus proteus corresponds with the Drepanoistodus
inconstans Zone together with the Triangulodus subtilis/Gothodus
microdentatus Zone of Kopingsklint (see chart II and fig. 15). The latter two
zones are equivalent to the Zone of Plesiomegalaspis armata, defined by
Tjernvik (1956) at Kopingsklint (see figs. 16 and 19).
The Prioniodus elegans Subzone of Sergeeva seems to be characterized by
the total range of Prioniodus elegans emend. herein. Thus defined, this
subzone is correlative with the Prioniodus elegans/Oelandodus elongatus
Zone together with the Stolodus stola Zone and the Protopanderodus
rectus/Oelandodus costatus Zone of section 6 (see chart III and figs. 15 and
19). These zones are equivalent to the lower portion of the Zone of
Plesiomegalaspis planilimbata, defined by Tjernvik (1956) at Aleklinta
(fig. 17 and 19).
Sergeeva's Subzone of Prioniodus evae seems to be characterized by the
concurrence of the ranges of Oepikodus evae emend. herein, Paroistodus
parallelus emend. herein, Stolodus stola emend. LINDSTROM, Protopanderodus
rectus emend. LINDSTROM, Oistodus lanceolatus emend. herein,
Drepanoistodus forceps emend. herein, Scolopodus rex LINDSTROM and
Prioniodus crassulus emend. herein. In the rock-sequence of north-western
Oland only Oistodus lanceolatus and Prioniodus crassulus appear after the
first occurrence of Oepikodus evae (fig. 15). If, however, Sergeeva's Subzone
of Prionoidus evae is considered to be characterized by the total range of