Porenschuppen und Sinneslinien des Thelodontiers Phlebolepis elegans Pander

Some scales (Pore-scales) of the Thelodontian Phlebolepis elegans Pander from the Lower Ludlow (Paadla Beds, Islands of Oesel) are penetrated by one or more channels which extend on the inner side of the scales in the shape of tubes. The position and number of these channels is quite arbitrary. In no way do the channels affect the normal, histological construction of the scales and similarly they cause no pathological change or resorpiton in the dentine of the scale. They originate either simultaneously with the scales, or were formed before their growth. In cases of complete preservation of the scale-cover of Phlebolepis one sees that the pore-scales are arranged in rows on the head and body. Pore-scales have, as yet, be found on no other genera of Theolodontian. The channels of these pore-scales are interpreted as branch channels of the lateral organ. This would be the first case of a lateral organ having been found among Thelodontians. Further investigation of suitable material might bring new criteria for determining the systematic position of the Thelodontians among the Agnathans. Final confirmation must be left to a study of the large Phlebolepis collections in New York (Patten collection) and in Tallinn (Luha and Bölau collections).