Meeting Abstract
I described the development of the tongue and tongue sheath in sectioned embryos of colubrid snakes that had been staged following the criteria of Zehr (1962). Most specimens belonged to the thamnophiine genera Nerodia and Storeria. There was a general pattern with some variation among species. Before stage 29, the tongue is an undifferentiated elevation in the floor of the oral cavity. By stage 29, the anterior end of the tongue is forked and detached from the floor of the mouth; two bundles of longitudinal muscles have begun to differentiate. By stage 32, the tongue sheath has begun to form and extend caudally; the verticalis and transverse muscles have differentiated. At stage 34, the tongue sheath has extended posterior to the skull. In later embryonic stages, an additional layer of tissue encircles the caudal tongue sheath. By the last embryonic stage, the histology of the tongue is very similar to what has been described in adults.
