22 



NEBRASKA ORNITHOLOGISTS' UNION 



than wise, urging- Professor Marsh to consider the advisability of con- 

 cealing this specimen because it savored too much of evolution. They 

 admitted its genuineness, seeing it was before their eyes in the cabinet, 

 but denied that the facts should be made known by allowing it to 

 stand so publicly on exhibition in the cases, and proposed as a remedy 

 that an opaque curtain be so arranged as to be drawn over the speci- 

 men to conceal it. The case containing the polydactyl horses, as well 

 as that containing Hesperornis and Ichthyornis, seemed to trouble them 

 especially. Here were men and women afraid of the truth, and we see 

 a repetition of that marvelously execrable fact that secular truths are 

 not sacred while religious truths are. 



Fisr. 55 — Young fowl 



ANCIENT AND MODERN WINGS 



Fig. 51 — A young Hoatzin, a bird of South America, using its iingers and toes in 

 climbing as ancestral birds probably did. Later the thumb and finger become 

 shortened. See Figs. 53 and 54. 



Fig. 52 — A restoration of the hand-wing of Afchaeopteri/x, the Lizard-bird, showing 

 three free digits and two fused digits for support of wing. 



Fig. 53 — Ventral view of the right wing of a young Hoatzin, OpisfJtocoinKfi cri>^fiitHS, 

 showing relatively long free thumb and index finger used in climbing. To facil- 

 itate this end the three outer digital primaries remain undeveloped for some time. 

 Observe that the hand is longer than the forearm in the young, and that thumb 

 and index fingers have claws. 



Fig. 54 — Ventral view of the right wing of an adult Hoatzin for comparison with the 

 manus of the young Hoatzin. The hand, or wing, is now shorter than the fore- 

 arm ; the thumb is considerably reduced ; and the claw of the thumb persists as a 

 small callus, while that of the index finger is suppressed. 



Fig. 55^ Ventral view of right wing of a young fowl {GaUiis bcinkiva) an ally of 

 Hoatzin. Having exchanged arboreal for terrestrial habits the hand or wing is 

 shortened; the thumb alone retains a claw; the index finger does not project be- 

 yond the wing membrane; and the development of the three distal digital quills is 

 arrested. 



