THE BOOTES IN BIRDS. 163 



It presents, ou the median line, a thin and very salient ridge, named the brisket 

 {rariiia or keel) (Figs. 101), 14; 111, b. 2), which in a remarkable manner 

 multiplies the points of atta(;hment of these muscles. The anterior border 

 offers in its middle a small eminence of insertion, the episternal (Figs. 10!), 15 ; 

 111, A 2). Laterally, two articular grooves are seen which correspond to the 

 coracoids. The posterior border is cut by two notches which are often converted 

 into foramina (Fig. HI, b 3, :^). On the lateral borders are observed small 

 double articular facets answering to the inferior ribs. The angles which separate 

 these two borders from the anterior are both prolonged into a little eminence, 

 named by some authors the costal process (Fig. Ill, a 33). 



In the Fowl, the sternum is not so strong as in the Goose or Duck. On 

 each side of the brisket it shows two wide notches, which greatly reduce its 

 substance. These notches (Figs. 109, 18, 19 ; HI, a 6, 7), closed in the fresh 

 state by membranes, are distinguished as external and internal. The latter, of 

 greater size than the former, extends nearly to the extremity of the bone. 

 From this division of the lateral plates of the sternum, result two long and 

 slender processes directed backwards (Figs. 109, 16, 17 ; 111, a 4, 5). The 

 external terminates by becoming widened, and forming a kind of bony plate, 

 which covers the last inferior ribs. 



The sternum of Pigeons is distinguished by the enormous development of 

 the brisket. The two notches of the Fowl are also met with in these birds, but 

 the internal is nearly always converted into a narrow foramen. 



This comparative study of the sternum in the chief domesticated birds, leads 

 us to appreciate the correctness of the principles just enunciated, with regard 

 to the form and extent this bone may exhibit. The Gallinaceous Birds, properly 

 so called, which fly Uttle and badly, have the sterniiai singularly weakened by 

 the deep notches cut in its lateral parts. With Palmipedes, the sternum is wide 

 and but slightly notched, so that the Goose and Duck, which waddle along so 

 awkwardly in our poultry yards, are capable of sustaining long and rapid flight, 

 like that of the wild individuals of the same species. "With regard to Pigeons, 

 which are well known to l)e swift and powerful flyers, may this advantage not 

 be due to the extraordinary development of the keel which constitutes the 

 brisket ? 



Ribs (Fig. 109, /, etc.). — In the Fowl and Pigeon there are seven pairs 

 of ribs ; and in the Duck nine pairs. Articulated superiorly with the dorsal 

 vertebrae, as in Mammals, these bones are provided, near their middle, with a 

 flat eminence which commences at the posterior border, and is directed back- 

 wards and upwards, to rest by its free extremity on the external face of the next 

 rib. These eminences (Fig. 109, 20) form an epiphysis at an early period, and 

 are usually absent in the first and last ribs. They concur in an efficacious 

 manner to increase the solidity of the thorax. 



The costal cartilages of the Mammalia, are in Birds often transformed into 

 veritable inferior ribs, joined to the superior ribs by a diarthrodial articulation 

 (Fig. 109, j). These pieces are long and strong, and all terminate at their lower 

 extremity by a double facet which articulates with the lateral border of the 

 sternum ; they are nearly always absent in the two first ribs. It is not rare to 

 see the last united to the one before it, instead of passing directly to the sternum ; 

 in which case it comports itself like the asternal ribs of Mammals. 



Anterior Limbs. Shoulder-bone. — The shoulder comprises : a scapula ; a 

 particular bone named the coracoid by Cuvier ; and a clavicle, which forms, in 



