A REDESCRIPTION OF THE ANOMALOCYSTITID MITRATE RHENOCYSTIS-LATIPEDUNCULATA FROM THE LOWER DEVONIAN OF GERMANY

The anomalocystitid mitrate Rhenocystis latipedunculata, from the Lowe r Devonian Hunsruckschiefer of Rhineland, Germany, is reconstructed an d redescribed. Rhenocystis is characterized by transverse, terrace-lik e ridges on two antero-posteriorly elongate, postero-lateral areas of the dorsal head skeleton and on the posterior third of the ventral hea d skeleton; the relatively small size of the ventral plates of the sec ond transverse row; a suture between the mid-ventral plates of the fir st and third row; the relatively large size of the placocystid plate; the presence of rocking articulations between dorsal and ventral fore tail plates; a transversely expanded and recumbent anterior styloid bl ade; a robust, spike-like posterior blade; and four morphologically di stinct regions in the hind tail. Rhenocystis closely resembles Placocy stites forbesianus from the middle Silurian of England and Victoriacys tis wilkinsi from the upper Silurian of Australia, with which if forms a clade within the anomalocystitids of boreal type.