CHAPTER XVII ON THE THEORY OF TRANSFORMATIONS, OR THE COMPARISON OF RELATED FORMS

the series ( H ) is a skull of Equus, in its own corôÙreôÙsponôÙding network; and the intermediate stages ( B 〓 G ) are all drawn by direct and simple interpolation, as in Mr Heilmann〙s former series of drawings of Archaeopteryx and Apatornis . In this present case, the relative magnitudes are shewn, as well as the forms, of the several skulls. Alongside of these reconstructed diagrams, are set figures of certain extinct 〜horses〝 (Equidae or Palaeotheriidae), and in two cases, viz. Mesohippus and Protohippus ( M , P ), it will be seen that the actual fossil skull coincides in the most perfect fashion with one of the