310 Dr. H. Woodward — On Wingless Birds. 



one bone, tlie furculum) also act as supports, and tend to resist, — by 

 their union with the shoulder, at each end, and with the ridge of 

 the sternum in the centre, — the pressure of the wing-muscles in 

 flight. The bones of the wing, or fore-limb, are the humerus, the 

 radius and ulna, the former of which is small and slender. The 

 carpus consists of three bones (the metacarpals), the two outermost 

 digits are absent, and the remaining three phalanges are anchylosed 

 together. The thumb sometimes carries a claw, as in the Ehea, 

 Ostrich, Screamer, etc. 



In the young chick we find the radial and ulnar carpal bones are 

 distinct. These become united with the radius and ulna in the adult. 



In ArchcBopteryx they are seen to be distinct, and all three 

 phalanges are provided with claws. (See Dames on the Berlin 

 ArchcBopteryx.) 



The pelvic arch, and hind-limb. — The posterior, or "pelvic arch," 

 is composed of the ilium, the ischium, and the pubis ; these bones 

 are always anchylosed together and united to the sacral region of 

 the spine. 



The Ostrich is the only bird in which the two pubic bones are 

 united by a symphysis-pubis. The hind-limb consists of the femur, 

 tibia and fibula, tarsus, metatarsus, and phalanges. The femur in 

 birds is a short bone. The tibia is long, and has a thin tapering 

 fibula attached to it. 



The ankle-joint is placed, as in Eeptiles, between the proximal 

 and distal portions of the tarsus, the astragalus and calcaneum being 

 united with the tibia and the distal portion to the 2nd, 3rd, and 

 4th metatarsals to form the ' tarso- metatarsal bone.' 



The leg in birds varies enormously in length, as may be seen by 

 comparing the Waders and Perchers. 



There is a remarkable constancy in the number of joints to the 

 toes of the foot in almost all birds, thus : — I. The hallux, or hind-toe 

 (=to the thuinb), has two joints; the II. inner toe has 3 joints; 

 the III. or middle-toe has 4 joints ; and the IV., or outer-toe, has 

 5 joints. [The fifth toe is never present, and the ' hallux ' is 

 frequently absent.] 



But no rule is without exceptions. Thus the " Swifts " have 

 never more than 3 joints to the third and fourth toes. The " Goat- 

 sucker " has 2 joints less on the outer or 4th toe. The inner big-toe 

 (II.) and the hallux disappear in the Ostrich. 



The hallux is frequently absent both in Natatorial (Swimming) 

 and in Cursorial (or Running) birds. [Compare the Avian foot and. 

 pelvis with that of the Dinosaurs.] 



Scarcity of Avian Fossils. — Although we have positive evidence of 

 the existence of Birds in the Jurassic period, yet their presence, as 

 fossils, is most uncommon. 



It was at one time surmised that the numerous bipedal, three-toed 

 foot-prints, preserved upon the surface of Connecticut Sandstone of 

 Triassic age, had been made by birds ; but it may now be argued, 

 with equal probability, that these tracks may have been left by 

 Dinosaurian reptiles, having tridactyle hind-feet upon which they 



