File:The American journal of science (1898) (18150398112).jpg

Title: The American journal of science
Identifier: americanjournal461898newh (find matches)
Year: 1880 (1880s)
Authors:
Subjects: Science
Publisher: New Haven : J. D. & E. S. Dana
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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C. E. Beecher—Origin and Significance of Spines. 343 birds are nearly all that remains of the external fingers, or digits. In the Hoactzin of South America (Opisthocomus cristatus), the young bird has a thumb and index finger, both provided with claws, and climbs about much like a quadruped, using its feet, fingered wings, and beak. According to Lucas,43 a rapid change " takes place in the fore limb during the growth of the bird, by which the hand of the nestling, with its well- developed, well-clawed fingers, becomes the clawless wing of the old bird with its abortive outer finger." Similar claws or spurs occur on a number of other birds, some having functional wings, as in the example just described, and others having only vestiges of wings, as in the Wingless Bird of New Zealand (Apteryx, figure 69). 66 67 68 TO P
Text Appearing After Image:
Figure 66. Female of Lernceascus nematoxys. A parasitic Copepod, showing suppression of limbs. Enlarged. (After Claus.) Figure 67. Horse-Shoe Crab, Limidv.s polyphemus, showing telson spine and abbreviated abdomen. Reduced. Figure 68. A Devonian Phyllocarid, Echinocaris socialis, showing spiniform telson and cercopods. Figure 69. Wing of Apteryx australis. x ;. (After Romanes.) Figure 70. Skeleton of right fore limb of the Jurassic Dinosaur, Igicanodon bernissartensis, showing suppressed first digit, x ¥^. (After Dollo.16) Another example may be taken from the Dinosaurian Kep- tiles. The Jurassic genus Iguanodon, from England and Belgium, belongs to a group (Ornithopoda) in which the num- ber of functional digits varies from three to five in the manus, and from three to four in the hind feet. In this genus, the hind foot had three functional toes, representing the second, third, and fourth of a normal pentadactyl foot. The first is represented by a slender tarsal bone alone, while the fifth is completely suppressed. The manus, or fore foot, of this ani-

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