THORAX AND RIBS. 31 



subsequent ribs increase in length to the ninth inclusively, and thence 

 diminish to the lowest false rib, as will be seen by this table. The first 

 rib measures 28 inches ; second rib, 35i in. ; third rib, 391 in. ; fourth rib, 

 JrJri in.: fifth rib, 491 in.; sixth rib, 52 in.; seventh rib, 53 i in.; eighth 

 rib, 54* in. ; ninth rib, 544 in. ; tenth rib, 534 in. ; eleventh rib, 52i in. ; 

 twelfth rib, 49 in. ; thirteenth rib, 45 in. ; fourteenth rib, 42 in. ; fifteenth 

 rib, 37* in. ; sixteenth rib, 341 in. ; seventeenth rib, 32 in. ; eighteenth rib, 

 281 in. ; ninteenth rib, 26 in. ; twentieth rib, 21 in. 



From the second to the sixth rib inclusively, they are broad near 

 the vertebral extremity ; the broadest being the fifth, which measures four 

 inches (Plate XXII. Fig. 4) ; after the seventh, they lose the flattened form 

 at this extremity, and resemble the human ribs. The head, in each of the 

 true ribs, presents an articular surface. The tubercle of each rib has also 

 an articular surface, to correspond with that of the transverse process of 

 the vertebra. The anterior edges of the ribs are sharpened ; the posterior 

 are rounded, and present a broad groove for the intercostal vessels, but 

 this groove is less distinct in the anterior ribs. The sternal extremities 

 are rough for the cartilaginous attachment. 



The second rib on the right side (Plate XXIII. Figs. 1 and 2) has been 

 broken six inches from the sternum, and reunited irregularly by osseous 

 matter, which is perfectly smooth anteriorly, showing that the fracture had 

 been of long standing. Near the sternum is a considerable irregularity, 

 owing to uneven union. 



The last two false ribs on the right side are co-ossified for the space 

 of eight inches ; the result of a fracture near their vertebral attachments : 

 the union of these ribs, at its broadest part, 'measures eight inches (Plate 

 XXIII. Figs. 3 and 4). These bones are perfectly smooth within, and 



