378 



ZOOLOGY 



SECT. 



with the pterygoids and the rostrum. The pterygoids (pt., PTG.) 

 are rod-shaped and set obliquely ; each articulates behind with the 

 quadrate, and, at about the middle of its length, with the basi- 

 pterygoid process, a small faceted projection of the base of the 

 rostrum. There is no vomer in the Pigeon. 



The mandible of the young Bird consists of a replacing bone, 

 the articular (ar., ART.), and four investing bones, the angular 

 (an., ANG.), supra-angular (s.an., S. ANG.), dentary (d., DNT.), 

 and splenial (SPL.), all having the same general relations as in 

 the Lizard. The hyoid apparatus (Fig. 1043) is of characteristic 

 form, having an arrow-shaped body (b. hy.) with a short pair 

 of anterior cornua (c. hy.) derived from the hyoid arch, and a 



long pair of posterior cornua (c.br., 



cp.br.) from the first branchial. The 

 b h __p, columella (Fig. 1044) is a rod-shaped 



bone ankylosed to the stapes, and 

 c bearing at its outer end a three-rayed 



cartilage, the extra-columella (e.st., 



b.bn 



b.br.z 



s.al 



st 



c br 



e/b.br- 



e.st. 



FIG. 1044. Columba livia. The columella auris 

 (magnified). The cartilaginous parts are dotted. 

 e. st. extra-stapedial ; f . st. infra-stapedial ; s. st. 

 supra-stapedial ; ft. stapes. (From Parker's 

 Zootomy.) 



i.st., s.st.), fixed to the tympanic 

 membrane. 



F. io43.-coiumba livia. Hyoid The shoulder-girdle (Fig. 1038) is 

 apparatus. The cartilaginous parts quite unlike that oi other Cramates. 



are dotted, b.br. 1, b.br. ~, basi- mi r -i, vl 



branchials; b.hy. basi-hyal ; c.br. Inere IS a pair OI stout, pillar-like 



c ^*te^& hv ' hvoidcOTn "' coracoids (cor.) articulating with deep 



facets on the anterior border of the 



sternum, and directed upwards, forwards, and outwards. The dorsal 

 end of each is produced into an acro-coracoid process (acr. cor.), and 

 below this, to the posterior aspect of the bone, is attached by 

 ligament a sabre-shaped scapula (scp.) which extends backwards 

 over the ribs, and includes, with the coracoid, an acute angle, the 

 coraco-scapular angle. The glenoid cavity (gl. cv.) is formed in 

 equal proportion by the two bones ; internal to it the scapula is 

 produced into an acromion process. 



In front of the coracoids is a slender V-shaped bone, thefurcula 

 (fur.) or " merrythought," the apex of which nearly reaches the 

 sternum, while each of its extremities is attached by ligament to 

 the acromion and acro-coracoid processes of the corresponding 

 side in such a way that a large aperture, the foramen triosseum 



