Genus Rakvereprion Mierzejewski, 1978
Type species: Staurocephalites? balticus Eisenack,  1975
Diagnosis: " Jaw apparatus of placognath type with symmetric posterior  part
consisting of right and left
MI, basal and laeobasal plates.  Anterior part of the
apparatus unknown.
MIr almost straight, slightly  bent outwards in its anterior
part, elongate. Basal plate elongate, compressed  laterally, equal in length to
MIr, adhering to its outer margin.  MIl and laeobasal plate forming mirror
images of
MIr and basal  plate." (Mierzejewski 1978, p. 279).
Remarks. -The type species of the genus has been tentatively assigned by
Eisenack  (1975) to the genus
Staurocephalites Hinde, 1879. Actually,
however, the  latter name is
nomen dubium.
 Kielan-Jaworowska (1966) mentioned an undescribed apparatus with its  MI
MI and MII of Xanioprion Kielan-Jaworowska, attached one to the
other; the apparatus was assigned to  
Xanioprion sp. One may claim that
Rakvereprion is closely related  to Xanioprion, the main differences being in
the wholeness of the  apparatus elements in the former genus, while they are
split transversally in  the latter one. In fact,
Rakvereprion appears
intermediate between the  Mochtyellidae and Xanioprionidae.
Eisenack, A. 1975. Beiträge zur Anneliden-Forschung. - Neues Jahrbuch fĂĽr  Geologie und Paläontologie Abhandlunge,
Monatshefte, 150 (2), 227-252.
Kielan-Jaworowska, Z. 1966. Polychaete jaw apparatuses from the Ordovician  and Silurian of Poland and a comparison with
modern forms.
- Palaeontologia  Polonica 16, 1-152.
Mierzejewski, P. 1978. New placognath Eunicida from the Ordovician and  Silurian of Poland. - Acta Geologica Polonica 28, 2,
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