238 SYSTEMATIC SYNOPSIS. — CARINATA — PASSERES. 
Il. Opontroitca. — Birds with teeth, implanted in grooves. Vertebree saddle-shaped 
(heterocelous). Wings rudimentary, wanting metacarpals. Sternum without 
keel. Tail short. (Typified by the genus Hesperornis, from the Cretaceous of 
North America. Fig. 15.) 
IV. Ratitrz.— Birds without teeth. Vertebree (some) saddle-shaped. Wings rudi- 
mentary, or at most unfit for flight, with anchylosed metacarpals. Sternum 
without keel (as in Odontolce, fig. 15). Tail short. (Embracing the extinct 
Moas, and the living Ostriches, Cassowaries, Emeus, and Kiwis.) 
VV. Carinata#.— Birds without teeth. Vertebree (some) saddle-shaped. Wings devel- 
oped, with rare exceptions fit for flight, with anchylosed metacarpals. Sternum 
keeled. Tail short (as to its vertebrae, which are pygostyled). (Embracing all 
living birds excepting the Rate). 
V. AVES CARINATZH: ORDINARY BIRDS. 
The essential characters of this group, which includes all living birds excepting the 
ostriches and their allies (ratite or struthious birds), are the absence of teeth, the saddle-shaped 
faces of the best-developed vertebra, and the keeled breast-bone (fig. 56), in combination with 
the perfection of wing-structure in adaptation to aerial (or aquatic) flight. The metacarpals and 
three metatarsals are anchylosed (figs. 27, 34); the scapula and coracoid meet at less than a 
right angle (very rarely more), and the furculum is usually perfect (fig. 59). (In the flightless 
parrot of New Zealand (Stringops habroptilus), the sternal keel is rudimentary.) The caudal 
vertebrae are few, and’the last few (pygostyle, fig. 56) are peculiarly modified to support the 
tail-feathers in fan-like array. There is normally extensive post-acetabular anchylosis of the 
pelvic bones, which are normally separate there in the other groups (compare figs. 56 and 15). 
The division of Carinate birds has always exercised the judgment and ingenuity of orni- 
thologists ; no system that has been proposed has been universally adopted, and few if any of 
the major groups can be considered established and perfectly defined. The orders of Carinate, 
therefore, are still provisional. But a great assemblage of birds have been ascertained to 
agree (with few exceptions) in possessing certain characters, upon the combination of which 
may be based an 
I.— Order PASSERES: Insessores, or Perchers Proper. 
The feet are perfectly adapted for grasping by the length and low insertion of the hind toe, 
. great power of apposing which: to the front toes, and great mobility of which, are secured by 
separation of its principal muscle (flexor longus hallucis) from that which bends the other toes 
collectively (flexor profundus digitorum). The hind toe is always present, perfectly incumbent, 
and never turned forwards or even sideways; its claw is as long as, or longer than, the claw 
of the middle toe. The feet are never zygodactyle, nor syndactyle, nor semipalmate, nor 
palmate; the front toes are usually immovably joined to each other at base, for a part, or 
the whole, of the basal joints. No one of the front toes is ever versatile. The joints of the 
toes are always 2, 3, 4, 5, counting from the first (hinder one) to the fourth (outer front one). 
The toes are always four in number (excepting Cholornis). (Figs. 36, 37, 42, 43.) Various 
as are the shapes of the wings, these members agree in having the great row of coverts not more 
than half as long as the secondaries ; the primaries either nine or ten in number, and the second 
aries more than six. (Fig. 30.) The tail, extremely variable in shape, has twelve rectrices 
(with certain anomalous exceptions). The bill is too variable in form to furnish characters of 
groups higher than families; but its covering is always hard and horny, in part or wholly, — 
never extensively membranous, as in many wading and swimming birds, nor softly tumid, as in 
