Elementary text-book of zoology. Special part: Mollusca to man / by C. Claus ; translated and edited by Adam Sedgwick ; with the assistance of F.G. Heathcote.
- Carl Friedrich Wilhelm Claus
- Date:
- 1897
Licence: Public Domain Mark
Credit: Elementary text-book of zoology. Special part: Mollusca to man / by C. Claus ; translated and edited by Adam Sedgwick ; with the assistance of F.G. Heathcote. Source: Wellcome Collection.
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![carry the body raised from the ground; but in locomotion are used principally for pushing the body forward; they may also be used for clinging (Chamselion), climbing (Geckos), and digging. They usually end with five clawed digits. They are sometimes so short and rudi- mentary, that they have the appearance of stumps applied to the serpent-like body, and are without separated digits (Chamcesaura). In other cases rudiments of the posterior limbs alone exist (Pseudopus) (fig. 641), or anterior limbs only are present (Chirotes); or finally external limbs may be entirely absent (Anguis, Acontias, Ophi- saurus). The pectoral and pelvic girdles are however present, and in all Lizards except Amphisbcena there is at least a rudiment of the sternum, which increases in size as the anterior limbs become more developed, and then serves for the attachment of a correspond- ingly greater number of ribs. The ribs are only wanting on the most anterior cervical vertebrae, and sometimes on some of the lumbar as well as on the caudal vertebrae. The anterior ribs present a peculiar modification in Draco, being extremely long and serving to support lateral expansions of the skin, which can be used as wings. The cranial capsule (fig. 631) does not usually extend into the orbital region, behind which it is imperfectly closed by membranous structures (membranous interorbital septum). The squamosal is firmly attached to a strongly projecting process (parotic process) of the posterior temporal region. The hinder end of the maxilla is frequently connected with the postfrontral (Pf) by a bony bridge, the jugal (fig. 631 J), which encloses the orbit; while a bone (quadrato- jugal) passes from the jugal to the .quadrate, bridging over the temporal region. An important character of the Lizards as opposed to the Snakes consists in the fact that the bones of the jaws are not movable upon one another. Parts of the maxillo-palatine apparatus are indeed movably connected with the skull (Hatteria = Sphenodon excepted), especially the pterygoids, which are applied to the articular processes of the basisphenoid, and usually articulate with the quadrate; but the individual bones of the maxillo-palatine apparatus are firmly connected with one another, and with the anterior part of the skull. The pterygoids are firmly attached to the maxillaries by a transverse bone, and serve to support the parietal bones by a rod-shaped columella [a bone which extends from the parietal to the pterygoid on each side]. On the top of the skull the parietal bones and the occipital segment are connected by fibrous tissue, and in consequence are slightly movable upon one another. The quadrate bone is](https://iiif.wellcomecollection.org/image/b2813378x_0217.jp2/full/800%2C/0/default.jpg)
