374 SKELETON OF THE FOWL 



d, The columella and the hyoid apparatus. These 

 may conveniently be considered together, as the 

 columella is, according to most authorities, the 

 uppermost part of the hyoid arch, just as the 

 quadrate is of the mandibular. 



i. The columella is a minute and slender rod of 

 bone, the proximal end of which is expanded 

 into an oval plate, fitted into the fenestra 

 ovalis of the tympanic cavity; while the 

 outer or distal end, which is cartilaginous and 

 divided into three diverging arms, is attached 

 to the tympanic membrane. It serves to 

 convey the sound- vibrations from the tym- 

 panic membrane to the membrane closing the 

 fenestra ovalis, and so to the internal ear. 



Owing to its small size, the columella is 

 often lost in macerated skulls : it may, how- 

 ever, sometimes be found projecting from the 

 fenestra ovalis. 



ii. The hyoid apparatus is a bony framework, lying 

 in the floor of the mouth, and supporting the 

 tongue. It consists of a median jointed rod 

 of bone and cartilage, formed of glosso-hyal, 

 basi-hyal, and basi-brancMal ; to the sides of 

 which are attached in front the short cerato- 

 hyals, and further back, the elongated and 

 jointed thyro-hyals, the ventral ends of the 

 first branchial arches. 



II. THE APPENDICULAE SKELETON. 



A. The Pectoral Girdle. 



The pectoral girdle is stout, and is firmly connected with 

 the sternum to give support to the wings. It differs markedly 

 from that of the rabbit in the large size of the coracoid, 

 which is placed almost perpendicular to the scapula ; and in 

 the completeness of the clavicle. 



