1 68 



ANIMAL BIOLOGY. 



[Part I. 



Anterior to the true ribs are three free incomplete false ribs, 

 the form of which resembles the vertebral portion of the true 

 ribs. 



FIG. 54. STERNUM AND SHOULDER-GIRDLE. 



A. Sternum of fowl from below. B. Sternum and shoulder -girdle of frog 

 in diagrammatic section. C. The same from below, with upper part straight- 

 ened out. D. Scapula of rabbit. E. Shoulder-girdle of fowl. 



a. st. Part of coracoid which articulates with sternum, ac. Acromion. 

 b. st. Body of sternum, c. b. Costal border, c. g. Coracoid groove, c. p. 

 Coracoid process in fowl. ca. Carina or keel. cl. Clavicle, co. Coracoid. 

 co. b. Coracoid border, co. p. Coracoid process in rabbit, e. x. p. External 

 xiphoid process. /. Furcula. gl. b. Glenoidal border, gl. c. Glenoidal cavity. 

 h. cl. Hypocleidium. h. co. Head of coracoid. i. x. p. Internal xiphoid pro- 

 cess, m. ac. Metacromion. m. x. p. Middle xiphoid process, o. st. Omo- 

 sternum. r. Rostrum, sc. Scapula, s. sc. Supra-scapula. s. sc. b. Supra- 

 scapular border, sp. Spine, st. Sternum, x. st. Xiphi-sternum. 



The sternum of the fowl is a large and well-ossified struc- 

 ture. The central portion or body of the sternum (Fig. 54, b. st.) 

 is boat-shaped and concave dorsally, and is prolonged back- 

 wards as an elongated middle xiphoid process (m. x. p.). Ven- 

 trally there is a well-marked keel or carina (ca.). Anteriorly 

 the sternum is produced into a vertically-flattened rostrum or 

 manubrium (r. ), on either side of which, running backwards and 

 outwards along the front edge of the body, is a coracoid groove 

 (c. g.). On either side of the sternum there are three large pro- 

 cesses. The most anterior is the costal process (c. p.); behind 

 which, at the side, is the costal border for the articulation of the 

 ribs (c. b.). Posterior to this are two processes having a common 



