Ontogeny of cranial ossification in the small-mouthed salamander, Ambystoma texanum (Matthes)

The ontogenetic sequence of cranial bony structure from initial ossifications through metamorphosis in Ambystoma texanum is described on the basis of 128 cleared and stained specimens. For convenience of discussion nine stages are recognized on the basis of conspicuous events. Cranial bones ossify and are modified in a definite sequence, and comparisons of complete sequences among groups of salamanders may prove useful in classification and in better understanding of relationships.