UTRECHT MICROPALEONTOLOGICAL BUllETINS

found on bland, and in fig. 19 a biostratigraphical correlation of the conodont
faunas of these two regions has been given. In addition, the lithostratigraphic
and chronostratigraphic units, from which the Estonian faunas
originate, are entered in fig. 19.
The fauna of unit ArrM is very similar to that of the 6landian Cordylodus
ro tundatus Zone.
From the Varangu Member (= AmV) Viira et al. (1970) described two
conodont faunas. The older one is very similar to that of the Drepanoistodus
acuminatus Zone at Kopingsklint. The younger fauna of the Varangu
Member is quite comparable with that of the Drepanoistodus numarcuatus/
Paroistodus amoenus Zone of bland. This would imply, that the Varangu
Member is time equivalent to the "Ceratopyge shale" (= the Zone of
Shumardia), distinguished by Tjernvik (1956) in north-western bland
(figs. 16, 18 and 19).
In the fauna from unit Bra, reported by Viira et al. (1970, p. 154), two
conodont assemblages may be distinguished. Most probably, the older of
these assemblages is correlative with the Prioniodus deltatus Assemblage, and
the younger one with the Drepanoistodus inconstans Assemblage of northwestern
bland. The Drepanoistodus inconstans Assemblage Zone was proved
to be equivalent with the lower portion of the Zone of Plesiomegalaspis
armata, defined by Tjernvik (1956) at Kopingsklint (see chapter m.2.,
figs. 16 and 19).
The conodont fauna of unit Brb, given by Viira et al. (1970, p. 154), also
permits the distinction of two assemblages. The correlation of these assemblages
with our assemblages is more difficult, because of the occurrence of
Oistodus lanceolatus. With the exception of Oistodus lanceolatus, the older
fauna of unit Brb is similar to the younger fauna of unit Bra and almost
equivalent to the fauna of the Drepanoistodus inconstans Zone at Kopingsklint.
On north-western bland Oistodus lanceolatus emend. herein appears at
a much higher stratigraphic level and in a conodont assemblage of quite
different composition. It seems quite possible, therefore, that Oistodus
lanceolatus as reported by Viira et al. is not synonymous with our Oistodus
lanceolatus emend. herein.
Compared to the older fauna of unit Brb, the younger fauna of this unit
only lacks Distacodus peracutus, Paltodus inconstans (both elements of
Drepanoistodus inconstans emend. herein) and Acodus deltatus (= element
of Prioniodus deltatus emend. herein). The occurrence of Cordylodus angulatus
and the absence of Drepanoistodus inconstans emend. herein in this
younger assemblage of unit Brb might indicate, that it is younger than the
Triangulodus subtilis/Gothodus microdentatus Zone and older than the