The hyoid apparatus of the rat consists of an anteroposterior compressed and somewhat arched basihyal, the small anterior cornua and the more prominent posterior cornua. The ceratohyal is the only movably articulated element of the anterior cornu and is generally lost during the normal methods of preparing skeleton. The absence of stylohyal has resulted in modifications in the origins and insertions of Mm. stylohyoideus, styloglossus, and stylopharyngeus. The study of the hyoid region of rats, gerbils and squirrels supports the view that the muroid rodents have originated from the more generalized squirrel-like forms.