390 



ZOOLOGY 



SECT. 



cavity, sending off an orMtal process {orb. pr.) from its anterior mar- 

 gin, and presenting below a condyle for articulation with the man- 

 dible ; it is freely movable upon its tympanic articulation, so that 

 the lower jaw has a double joint as in Lizards and Snakes. 



The palatines (pi, PAL.) have their slender anterior ends anky- 

 losed with the maxilla, their scroll-like posterior ends articulating 

 with the pterygoids and the rostrum. The pterygoids {^^t., PTG). 

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

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

 ])terygoid ]jrocess, a small facetted 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 (cir., ART.), and four investing bones, the angular (a»., 



ANG.), supra-angular (s.an.,S.ANG.), 

 dentary (d., DNT.), and splenial 

 (SFZ.), all having the same general 

 relations as in the Lizard. The 

 hyoid-apjMratus (Fig. 1032), is of 

 _^ . characteristic form, having an arrow- 



i.br-f-^:^ shaped body (b. hy.) with a short pair 



b.br.z 



— ep-ir" 



v.st. 



Fig. 1033. — ColuTUba livia. The columella auris 

 (magnified). The cartiljiglnoua parts are dotted. 

 e. St. extra-stapedial ; i. st. infra-stapedial ; a. st. 

 supra-stapedial ; st. stapes. (Fi-om Parker's 

 Zootomy.') 



Pig. 1032.— Columba livia. Hyoid 

 ap23aratus. The cartilaginous parts 

 are dotted. 6. hr. 1, basi-branchials ; 

 h.hy. basi-hyal ; c.hr. cerato-brauchial; 

 c. hy. hyoid cornu ; ep. hr. epi- 

 branchial. 



\ /of anterior cornua (c. hy.) derived 



from the hyoid arch, and a long 

 pair of posterior cornua (c.br., ep.br.) 

 from the first branchial. The 

 columella (Fig. 1033) is a rod- 

 shaped bone ankylosed to the stapes, 

 and bearing at its outer end a three- 

 rayed cartilage or extra-colicmella (e.st , i.st., s.st.) fixed to the 

 tympanic membrane. 



The shoulder- girdle (Fig. 1027) is quite unlike that of other 

 Craniates. There is a pair of stout, pillar-like 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 p}rocess (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 



