300 THE VERTEBRATE SKELETON. 



Order 3. CARINATAE. 



This order includes the vast majority of living birds. 

 The cervical vertebrae have saddle-shaped articulating surfaces 

 (except in the Ichthyornithiformes). The posterior caudal 

 vertebrae are ankylosed forming a pygostyle. The quadrate 

 articulates with the cranium by a double head. In all except 

 the Tinamidae the vomers are narrow behind and not inter- 

 posed between the palatines, pterygoids and basisphenoidal 

 rostrum. The sternum has a median keel, and the anterior 

 limbs are in the great majority of cases adapted for flight. 

 Clavicles are well developed, and the scapula and coracoid are 

 nearly at right angles to one another. The various groups 

 into which the Carinatae are divisible are shown in the table 

 on pp. 40 42. Their special characters will not be dealt with. 



FIG. 55. Gallus barikiva var. domesticus. THE LEFT HALF OF THE SKELETON. 

 The skull, vertebral column, and sternum are bisected in the median 

 plane. (After Marshall and Hurst.) 



A, acetabulum. B, cerebral fossa. CB, cerebellar fossa. CL, clavicle. CO, coracoid. 

 CR, cervical rib. C l = one, first cervical vertebra. FE, femur. HC, ventral end of clavicle. 

 HU, humerus. HY,hyoid. IF, ilio-sciatic foramen. IL, ilium. IS, ischium. L, lachrymal. 

 MC 3, postaxial metacarpal. MN, mandible. MS, xiphoid processes. MT, tarso-metatarsus. 

 MT 1, first metatarsal. N, nasal. OP, optic foramen. P, premaxilla. PB, pubis. PL, 

 palatine. PY, pygostyle. R, radius. RC, radial carpal. S, keel of sternum. SC, scapula. 

 T, tibio-tarsus. TH 4, fourth thoracic vertebra. U, ulna. UC, ulnar carpal. UP, uncinate 

 process. Z, infra-orbital bar. 1, 2, 3, 4, first, second, third and fourth digits of pes. 3, pre- 

 axial, 4, middle, and 5, postaxial digit of manus. 



