VII. On the modifications of the first and second visceral arches, with especial reference to the homologies of the auditory ossicles

The phylogenetic development of the first visceral arches shows us some most interesting changes of function, which we can follow upwards from the lower Selachians to the highest Mammals. Originally entirely devoted to respiration as gill-bearing structures, the whole hyoidean arch becomes soon a factor in the alimentary system.