168 ELEMENTS OF OENITHOLOGT. 



much longer, and segmented, pair are attached, one on either 

 side, to the hinder part of the basi-hyal, and these are called the 

 " greater horns," greater cornua, or thyro-Tiyah. It is these 

 which are so prolonged and so singularly fixed in the Wood- 

 peckers, where they serve as a spring to help the darting for- 

 wards of a spear-like tongue borne at the end of a long and 

 slender basi-hyal. 



The Limbs. 



The Appendicular Skeleton. — This, as before said *, consists of 

 two limb-girdles, each supporting a pair of limbs — one thoracic, 

 the skeleton of the shoulder or shoulder-girdle, the other pelvic, 

 the skeleton of the hip. 



The thoracic limb-girdle — which is also 'called the scapular 

 arch — is firmly attached, as before said, to the ventral por- 

 tion of the thoracic part of the axial skeleton, namely, to 

 the anterior end of the sternum, where it is fixed into the 

 grooves there situate. It has no other connection with 

 the axial skeleton. The girdle consists of three parts or 

 elements on either side, and the bone of the upper arm — the 

 proximal bony segment of the Umbs — is articulated to two of 

 these three elements at the point where they meet. These 

 three elements are termed respectively the coraeoid, the clavicle, 

 and the scapula. 



The girdle is actually completed below by the junction of 

 the two lateral portions of the clavicle. 



The Coraeoid. — This is a bone which is not only invariably 

 present, but is the strongest and most important one of the 

 thoracic limb-girdle. It is that bone which at one end is 

 fitted into the groove of the sternum, while at the other it is the 

 main support of the bones of the wing. Its size is directly 

 related to the use of the wing, and is immense in the Penguin, 

 which has to exert so much force with its wings, and which 

 employs the motions of flight in the denser medium of water, 

 as this bird may be said to fly submerged. It is a straight, 

 stout bone, more or less expanded below for its implantation 

 in the sternum, and bifurcating at its upper end into two pro- 

 cesses which unite with the other elements of the " scapular 

 arch." One of these, that which joins the scapula, presents at 



* See ante, p. 168. 



