The cranial and some other musculature of characoid fishes of the tribes Cynodontini and Characini is described and compared. The tribes are redefined on the basis of myological and associated osteological characters. It is shown that some of these characters are shared specializations which unite the tribes in the subfamily Characinae.
An attempt is also made at a functional description of the jaw mechanism of Rhaphiodon. A remarkable example of parallelism is noted between a cynodontid (Rhaphiodon) and a cyprinid fish (Macrochirichthys). The cranial musculature of the latter is described.