232 VERTEBRATES. 



conspicuous neural and lateral processes, and the large, 

 terminal, triangular pygostyle which supports the tail 

 feathers (rectrices). 



How many cervical vertebrae are there ? How many of 

 them bear evident ribs ? How many thoracic vertebrae are 

 there? How many thoracic ribs bear uncinate processes? 

 How many sacral vertebrae are there ? How many caudal ? 



III. The Sternum. Study the sternum. Note the fol- 

 lowing parts : 



1. A large, squarish, shovel-shaped 

 body, which closely covers the tho- 

 racic cavity, and extends backward 

 some distance over the abdomen. 



2. A large, triangular keel, borne 



on the median ventral line of the 

 STERNUM OF SPARROW 



FROM RIGHT SIDE body of the sternum. Note that both 



(natural size) : b, ^ body and ^Q keel are composed 



body ; k, keel ; m, ma- * . f 



nubrium or rostrum ; oi very thin plates ot bone, with sur- 

 cg, coracoid groove; faceg m i nute ly roughened for the 



cp, costal process; x, 



lateral xiphoid pro- attachment of muscles, and strength- 



cess ; sp, space filled d b thickened mar cn ns . 



in life by membranes. * 



3. A stout, median rostrum (or 



manubrium), forked at its tip, which projects forward, 

 and obliquely upward from the base of the keel, at the 

 front of the body of the sternum. 



4. A pair of sharp, triangular costal processes project- 

 ing forward from the anterior angles of the body. The 

 lateral borders of these processes are thickened to form 

 the costal surfaces bearing facets for articulation with the 

 sternal ends of the ribs. 



5. Between the costal processes and the rostrum, a 

 pair of coracoid grooves, in the anterior edge of the body 

 of the sternum, meeting on the median line. These grooves 

 are for articulation with corresponding ridges on the ends 

 of the coracoid bones. 



