. Animal Life and the World of Nature; A magazine of Natural History. . Fig. 1. Front, hind, and lateral aspects of a vertebra of a Python; «s, dorsal spine; np, lateral process; n, neural canal; ze and ze', pre- and post-zygapophyses; zi, zygantruni and zygospliene; c and c', anterior cup and posterior ball; ha and hp, ventral spine; a and d, articular surface for rib. Snake-vertebrae, as shown in Fig. 1, are characterised by possessing more interlocking surfaces than are to be found in those of most other animals, whereby the coils are formed with greater regularity and smoothness than would
. Animal Life and the World of Nature; A magazine of Natural History. . Fig. 1. Front, hind, and lateral aspects of a vertebra of a Python; «s, dorsal spine; np, lateral process; n, neural canal; ze and ze', pre- and post-zygapophyses; zi, zygantruni and zygospliene; c and c', anterior cup and posterior ball; ha and hp, ventral spine; a and d, articular surface for rib. Snake-vertebrae, as shown in Fig. 1, are characterised by possessing more interlocking surfaces than are to be found in those of most other animals, whereby the coils are formed with greater regularity and smoothness than would otherwise be the case, while the risk of dislocation is proportionately lessened. In addition to the ordinary articular facets known as pre- and post-zygapophyses, common to vertebrates in general, each vertebra of a snake has a wedge-shaped articular process known as the zygosphene which fits into a corresponding cavity—the zygantrum—in the adjacent surface of the next vertebra, whereby a most firm, and at the same time mobile, joint is secured. It is somewhat remarkable that a similar mode of articulation of the vertebras is met with in the iguana lizards of America. As other lizards get on perfectly well without such additional facets, it is difficult to understand why they should be developed in the iguanas, unless indeed it is a foreshadowing of the serpent type. Not that I mean to imply that iguanas are the ancestors of snakes; but it may well be that those lizards from which serpents took origin had vertebrae of this complicated type. If this suggestion prove true, it would be very difficult for those who believe that unaided survival of the fittest has been the prime cause in animal evolution to explain why these ancestral lizards should have acquired a type of vertebrae apparently necessary only to Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of th
Size: 1371px × 1823px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherlondo, bookyear1902
