PARTRIDGES, GROUSE, Sec. 



129 



dary numerous, rounded. The tail varies in length, form, and 

 the number of feathers, which are always more than twelve. 



The skeleton of these birds presents the following characters. 

 The cranium is proportionally small and narrow ; the septum 

 between the orbits generally complete ; the lower jaw w^ith a 

 large oblong aperture in the ramus. The cervical vertebrae are 

 generally fourteen ; the dorsal seven, and commonly anchylosed, 

 excepting the anterior two, as well as frequently the last two ; 

 the lumbar and sacral fourteen ; the coccygeal seven. The pel- 

 vis is very broad, but thin, the pubic bone linear and distinct. 

 There are generally seven slender flat ribs, with posterior linear 

 thin processes. The sternum, Fig. 43, a, b, c, d, e, /, y, is in 



Fig. 43. 



reality large and very broad ; but, having two very deep sinuses 

 on each side, leaving only two linear lateral processes, /, y, 

 having their interspaces filled w^ith membrane, it seems re- 

 duced to a very narrow plate, 6, e ; its crest, a, e, long and 

 anteriorly high, but with a very large and oblique anterior 

 sinus, «, b, and a thin crest-like process, b, between the cora- 

 coid bones. The latter, h, are rather stout, but spread little. 

 The furcula, i, in the form of the letter U, is very slender, with 

 a flattened triangular process beneath the union of its crura, 

 attached to the anterior edge of the crest of the sternum by a 



