All of the muscles under consideration have been grouped as either dorsal or ventral muscles, according to their embryonic origin, as described by Romer (1927) and Wortham (1948). This grouping probably represents accurately the phylogenetic origin of these muscles. The dorsal muscles probably were originally supplied by dorsal nerves--the femoral and peroneal--and the ventral muscles probably were originally supplied by ventral nerves--the obturator and tibial. This primitive muscle-nerve relationship has been relatively constant. Several previous workers have reported some dorsal muscles supplied by ventral nerves and _vice versa_. Those findings should be viewed with suspicion until verified, because the proximal parts of the tibial and peroneal nerves are intimately associated and their relationship is easily misinterpreted. I found a branch of the tibial nerve that is closely associated with, and distributed with, the peroneal nerve. That branch of the tibial nerve has been mistakenly considered a part of the peroneal nerve by some workers. My study revealed no definite exceptions to the expected innervation. TABLE 1. SYNONYMY OF THE MUSCLES OF THE LEG OF BIRDS ===============+===============+============+==============+============== | | Howell | Fisher & | Gadow (1891) | Hudson (1937) | (1938) |Goodman (1955)| Holmes ---------------+---------------+------------+--------------+-------------- ilio-tibialis |ilio-tibialis |extensor |extensor |extensor | | iliotibia- | ilio-tibia- | iliotibialis | | lis latera-| lis | lateralis | | lis | lateralis | ---------------+---------------+------------+--------------+-------------- ilio-tibialis |sartorius |extensor |extensor |extensor internus s. | |iliotibialis| ilio-tibia- | iliotibialis sartorius | |anterior | lis anterior| anticus ---------------+---------------+------------+--------------+-------------- ambiens |ambiens |ambiens |ambiens |ambiens ---------------+---------------+------------+--------------+-------------- femori-tibialis| | |femoritibialis|vastus externus | | | externus | lateralis | | | |(a) pars | | | | postica ---------------+ | +--------------+ {|femori-tibialis|vastus |vastus |(b) pars femori- {| externus | lateralis | lateralis | lateralis tibialis {+---------------+------------+--------------+-------------- medius {|femori-tibialis|} {|vastus |vastus {| medius |} {| medialis | medialis