This volume is a valuable contribution to the comparative morphology of the bird's skull, especially the development of the chondrocranium. The normal stages of the development of the chondrocranium of "Gallus" are described in detail to provide a model with which to compare cranial abnormalities developing from the experimental application of teratogenic material. A full discussion and evaluation of the various problems and conflicting interpretations concerning aspects of the avian chondrocranium are also provided.