XXI. On the osteology of Polydon folium

Abstract This Ganoid appears to have been first described, under the name of Squalus spatula, by Maduit in the ‘‘Journal de Physique’’ for 1774, pp. 384—-386, plate 2, fig. 1. Sub sequently, several zoologists described and figured the external appearance of Polyodon under the various synonyms of Polyodon (Lacépéde), Spatularia reticulata (Shaw), and Planirostra (Lesueur). The systematic position of the genus appears to have changed as often as its name. Originally regarded as an Elasmobranch, and subsequently as a Teleostean, it was reserved for H. Müller, in 1846, to elucidate its real affinities and to indicate its marked distinctness from the other families of Ganoids by establishing the suborder Chondrostei for its reception.