IV 



OSTEOLOGIA AVIUM. 



17. Phalanges of the anterior toes. 



18. Trochlea of the three bones of which the 



metatarsus is formed, to which the ante- 

 rior phalanges are articulated. 



19. Splint by which the hallux is articulated 



with the metatarsus. 



20. Phalanges of the hallux or hind toe. 



21. Tarsal bones anchylosed to the proximal 



extremity of the metatarsus. 



22. Sternum. 



23. Keel of the sternum. 



24. True fibs with their posterior styliform 



processes. 



25. False ribs not joining the sternum. 



26. Sternal ribs uniting the true ribs with the 



sternum. 



27. Ilium, "I 



28. Ischium, I together forming the pelvis. 



29. OspubisJ 



30. Ischiadic foramen. 



31. Obturator foramen. 



32. Cervical vertebrae. 



33. Dorsal ditto. 



34. Sacral ditto. 



35. Caudal ditto. 



Bones of the Head. 

 Plate I. 



1. Orbital septa. 



2. Bony case of the brain, formed by the 



parietal, frontal, and occipital bones an- 

 chylosed together. 



3. Os quadratum. 



4. Lacrymal bones. 



5. Malar or zygomatic bone. 



6. Nasal bones. 



7. Upper maxillary bones. 



8. Lower maxillary bones. 



In Plate IV. the numbers on the Crania show the same Bones in each. 



1.1. Palatine bones. 



2. 2. Ossa quadrata. 



3. 3. Interarticular bones. 



4. 4. Lateral portions of the palatine bones. 



5. 5. Intermaxillary bones. 

 6. Sphenoid bone. 



The head of Birds, as among Mammalia, forms the bony case for the brain, with an 

 anterior portion forming the face and jaws. The chief characters which can be derived 

 from the head are the shape of the vertex or top, whether it is convex or flattened, and 

 with or without a longitudinal depression in the centre : the shape of the maxillaries, 

 which give form to the bill : the portion of the ethmoid forming the septa between the 

 orbits, whether it is entire or not ; this character, however, varies with age, the form of 

 the lacrymal bones, and the direction in which their extremities point : the form of 

 the occiput, if with a large crest, a modified one, or none at all, and if indented with a 

 channel or not for the reception of the masseter muscles : the shape of the foramen 

 magnum : the shape of the palatine bones, and the interarticular uniting them with the 

 os quadratum, and whether any branch goes from them to the sphenoid, or what portion 

 of the roof of the mouth is cased with the intermaxillary bones. 



In the bones of the trunk the greatest modifications occur, particularly in the sternum ; 



