. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. lp7?>r—Squamosal ^—Digastric Muscle |r-Quadrate "•Pterygoid 5£>V \ digastric Muscle ^vf^\/ sQuadrate V Pterygoid rang ^ v^ Sphenopterygoid Muscle Palatine Transpalatine A Fig. 504. Jaw mechanism of the rattlesnake. A, with mouth closed; B, with mouth open. By a contraction of the digastric muscle the mouth is opened; at the same time another muscle draws the entire upper jaw, hinged on the quadrate and maxillary, forward; in this manner the fang
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. lp7?>r—Squamosal ^—Digastric Muscle |r-Quadrate "•Pterygoid 5£>V \ digastric Muscle ^vf^\/ sQuadrate V Pterygoid rang ^ v^ Sphenopterygoid Muscle Palatine Transpalatine A Fig. 504. Jaw mechanism of the rattlesnake. A, with mouth closed; B, with mouth open. By a contraction of the digastric muscle the mouth is opened; at the same time another muscle draws the entire upper jaw, hinged on the quadrate and maxillary, forward; in this manner the fang is swung out into striking position. (After Hilzheimer.) In poisonous snakes each fang is set in a socket in the corresponding maxillary. As the snake prepares to strike, it opens its mouth and moves the chain of upper jaw bones forward, thus swinging the fang out into striking position (Fig. 504). By moving the upper jaw elements posteriorly the snake returns its fangs to the resting position within the mouth cavity. In crocodiles and lizards the two parts of the lower jaw are joined in front by sutures, but in turtles they are fused into one solid mandible. The formation of an extensive hard palate, in which the maxillae, palatines, and pterygoids all take part, in the case of alligators and crocodiles causes the posterior opening of the choana on either side to be pushed back so far down the throat that these animals are able to drown their prey without being drowned themselves. This feat is accomplished by the aid of a curtain-like. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Walter, Herbert Eugene, b. 1867; Sayles, Leonard Perkins, 1902-. New York : Macmillan Co.
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Keywords: ., bookcentury1900, booksubjectanatomycomparative, booksubjectverte
