28 



ANATOMY OF VERTEBRATES. 



deepest; but the Barn-OAvl (^Strix Jiammeci) has but one on each 

 side; while Strix praticola shows a third intervening notch. ^ 



In the Cantores the sternum, fig. 15, is broadest behind, with 

 the lateral margins slightly concave, the costal, c, usually meeting 

 the rest of the margin at a very open angle. The keel has a 

 convex lower border meeting the concave front border at a sharp 

 anole : the manubrium <?, is bifurcate : the costal jjrocesses, d, are 



broad and flat: the posterior border 

 has a notch, f, usually of angular form, 

 on each side, near the lateral margin, 

 and with this outer boundary termi- 

 nally dilated. 



Among the Scansores the Toucans, 

 Barbets, Touracos, and Woodpeckers, 

 fig. 20, have a four-notched sternum : 

 the Cuckoos have but one pair of short 

 notches ; many Parrots (^Psittacus pro- 

 per, Pezo2)orus) have one pair of small 

 foramina, and Calyptorhynchus has the 

 sternum entire : it is keel-less in Stri- 

 (jops. In most parrots the costal border 

 is extensive ; the manubrium is trihe- 

 dral and truncate. None of the Scan- 

 sores have the manubrium bifurcate ; it 

 may be notched ; in most it is small ; in 

 some (^Cuculus, Painphastos) obsolete. 

 In the Volitores, as a rule, the 

 posterior border of the sternum has a 

 pair of notches on each side : the Eurylaim and Hoopoe have 

 one notch or foramen on each side. The Hornbills, Swifts, and 

 Hummino-birds have the sternum entire. In none of this 

 group is the manubrium bifurcate : it is wanting in Podarcjus, 

 Harpactes, Todus: the costal process is Avanting in some. In 

 the Swifts ( Cypsebis) the sternum corresponds in its proportional 

 magnitude with the superior length and power of wing A^'hich 

 characterizes the genus : the depth of the keel equals the breadth 

 of the entire bone. The manubrial process is wanting, but the 

 costal ])rocesses are moderately long and pointed. 



In the Humming-birds, which sustain themselves on the wing 

 during the greater part of the day, and hover above the plant 

 while extracting its juices, the sternum, r, s, fig. 18, is still 



Stermuu and scapular arcli, Woodpecker, 



a'icus). 



pl. 4, fig. 5. 



