A NEW CROSSOPTERYGIAN, YOUNGOLEPIS PRAECURSOR, GEN. ET SP. NOV., FROM LOWER DEVONIAN OF E. YUNNAN, CHINA

A primitive representative of crossopterygians - Youngolepis praecursor, gen.et sp.nov., is described from the Lower Devonian of eastern Yunnan. It is quite similar to porolepi-forms in the presence two external nasal openings, paired internasal cavities separated byan internasal ridge, a small fenestra ventro-lateralis on the ventral surface of the endocra-nium and a large medial profundus canal and several smaller lateral profundus canals inthe postnasal wall. In other respects this new form is quite close to osteolepiforms, e.g. thepresence of the processus dermintermedius of the lateral rostral plate,groups of pores for nervesto cutaneous sensory organs on dermal surface of the anterior cranial division, and the exten-sion of parasphenoid to the ventral side of the ethmoidal region. In its own particularities,Youngolepis praecursor agrees quite well with Powichthys from the early Lower Devonian of theCanadian Arctic Archipelago (the infraorbital sensory canal and the ethmoidal commissuralsensory can