New placognath Eunicida (Polychaeta) from the Ordovician and
Silurian of Poland
Piotr Mierzejewski
Acta Geologica Polonica 1978, 28, 2, 273-281
Eunicida with placognath jaw apparatuses make an extinct group of Polychaeta known since the Ordovician through
Permian. Some doubtful placognath eunicids were also reported from the Triassic. Isolated jaws were fot the first
time described by Hinde (1879) but they were erronously assigned to the Staurocephalidae. Their taxonomic position
has been recognized by Kielan-Jaworowska (1961, 1962, 1966) who described well-preserved jaw apparatuses from
the Ordovician and Silurian of
Poland.
[ABSTRACT, p. 273] Four species of placognath Eunicida (Polychaeta) represented by isolated jaws and jaw
apparatuses are described from Ordovician and Silurian erratic boulders collected along the Baltic coast in Poland.
One new genus (
Rakvereprion gen. n.) and two new species (Mochtyella angelini sp.n., and M. grazynae sp.n) are
erected.
PLATE 1
Abbreviations
: At anterior tooth, br basal ridge, Lt lateral tooth, MIl
left maxilla, MIr right maxilla, sr second ridge, sr' second ridge of
secondary maxilla,
sMIr seconadary MIr.
Mochtyella angelini Mierzejewski, 1978
Ludlovian erratic boulder No. MZ/142.

1a-b Holotype, jaw apparatus in two views.
2a-c Right MI in left lateral, dorsal, and right lateral views.
3a-c Left MI in left lateral, dorsal, and right lateral views.
Mochtyella grazynae Mierzejewski, 1978
Ludlovian erratic boulder No. MZ/142.

4a-c Holotype, right MI in left lateral, dorsal, and right lateral views.
5a-c Left MI in right lateral, dorsal, and left lateral views.
PLATE 2

1 Vistulella kozlowskii Kielan Jaworowska, 1961;  Upper Ordovician
erratic boulder No. MZ/25

2.
Rakvereprion balticus (Eisenack, 1975);
Upper Ordovician erratic boulder No. MZ/25.
Fig. 1. Diagrammatic sketch of jaw
apparatus of
Vistulella kozlowskii.
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