The development of facial muscles is studied in embryos of Tupaia belangeri, Tupaia javanica, Nycticebus coucang, Galago dimidovii, Tarsius bancanus, Callithrix jacchus, Colobus badius, Colobus verus, Nasalis larvatus, and Homo sapiens. 2. The facial muscles derive from a superficial blastema (anlage of platysma myoides) and another blastema laying beneath the first one (anlage of sphincter colli muscle). Both blastemas grow out from mesenchymal cells of the head after the anlagen of all other muscles are visible. 3. The myoblasts are arranged along the margines of the blastemas in a way that outline the run of the muscles. 4. Superficial muscle derives from the anlage of platysma, the profound muscles of the mouth and some of the rostral margine of the auricle derive from the anlage of sphincter colli muscle. 5. In species without sphincter colli muscle the myoblasts for muscles considered as derivates of sphincter colli (those muscles are identificable as derivates of sphincter colli in species which have it) grow out from mesenchymal cell directly. 6. The ontogenetic results show the principle of the way in which the facial muscles have evolved during phylogeny as described in comparative anatomy. 7. Muscles, which were present in an early state of phylogeny f. e. like sphincter colli muscle in the ancestors of Katarrhina, hav no anlage which later become reduced. 8. The facial muscles have a complete differentiation in an early state of prenatal development and the operate well until to the time of birth.
