[Illustration FIG. 60. A. Ventral view of the cranium of a Duck (_Anas boschas_). B. Cranium and mandible seen from the left side. × 1. 1. maxillae. 2. premaxillae. 3. anterior nares. 4. nasal process of premaxillae (fig. 59). 5. nasal. 6. frontal (fig. 59). 7. lachrymal. 8. postfrontal process. 9. parietal (fig. 59). 10. jugal. 11. quadratojugal. 12. quadrate. 13. condyle of mandible. 14. posterior articular process. 15. dentary at symphysis. } 16. basi-hyal. } (fig. 17. uro-hyal. } 59). 18. basibranchial. } 19. vomer. 20. palatine. 21. pterygoid. 22. anterior palatine foramen. 23. basitemporal. 24. foramen leading into tympanic cavity. 25. bristle inserted into posterior opening of carotid canal. 26. bristle inserted into posterior opening of Eustachian canal. 27. bristle emerging through anterior opening of carotid canal. Close by is seen the bristle emerging through the anterior opening of the Eustachian canal. 28. fenestral recess. 29. maxillo-palatine. 30. lambdoidal crest. 31. rostrum. I. II. IV. V. IX. X. nerve foramina.] The skull of the duck, like that of birds in general, is characterised (1) by its lightness, (2) by the contrast between the bones of the cranium proper and those forming the rest of the skull, for the bones forming the cranium proper are closely fused together, the sutures between them being nearly all completely obliterated in the adult, while the bones forming the face are loosely connected with the cranium proper; (3) by the prolongation of the face into a long toothless beak; (4) by the size of the orbits, and their position entirely in front of the cranium, so that they are separated from one another only by a thin interorbital septum. For purposes of description the skull may be divided into (1) The cranial portion. (2) The facial portion. (3) The mandible. (4) The hyoid. (1) THE CRANIAL PORTION. This is a rounded box expanded dorsally and posteriorly, but tapering antero-ventrally. In the young skull the divisional lines between the several bones can be easily seen, but in the adult they are quite obliterated. (_a_) The _dorsal surface_ is rounded, expanded in front and behind, but encroached upon in the middle by the cavities of the orbits. There is a prominent divisional line in front, separating it from the facial part of the skull. It is formed mainly by the _frontal_ (fig. 59, A, 6) and _parietal_ bones, but the frontals diverge a little anteriorly and enclose between them the ends of the _nasal processes_ (fig. 59, A, 4) of the _premaxillae_. Just in front of the orbit the outer margins of the frontals are either notched or pierced by a pair of foramina.