. On the anatomy of vertebrates [electronic resource] . the genera Tortrix and Homalopsis, and are reduced to a stillsmaller number in the poisonous serpents, in the typical generaof which the short maxillarybone supports only a singleperforated fang. The maxillary, fig. 268, e,diminishes in length with thedecreasing number of teethwhich it supports: the ecto-pterygoid, d, elongates in thesame ratio, so as to retain itsposition as an abutment againstthe shortened maxillary ; and 1 . Structure of the poison-teeth of the Rattle-snake the muscles implanted into the ectopterygoid communicate throu
. On the anatomy of vertebrates [electronic resource] . the genera Tortrix and Homalopsis, and are reduced to a stillsmaller number in the poisonous serpents, in the typical generaof which the short maxillarybone supports only a singleperforated fang. The maxillary, fig. 268, e,diminishes in length with thedecreasing number of teethwhich it supports: the ecto-pterygoid, d, elongates in thesame ratio, so as to retain itsposition as an abutment againstthe shortened maxillary ; and 1 . Structure of the poison-teeth of the Rattle-snake the muscles implanted into the ectopterygoid communicate through it to the maxillarybone the hinge-like movements backward and forward upon theginglymoid articulations connecting that bone with the prefrontaland palatine bones. As the fully developed poison-fangs areattached by the same firm basal anchylosis to maxillary sockets,which forms the characteristic mode of attachment of the simpleor solid teeth, they necessarily follow all the movements of thesuperior maxillary bone. When the external pterygoid is re-. 396 ANATOMY OF VERTEBRATES. tracted, the superior maxillary rotates backward, and the poison-fang is concealed in the lax mucous gum, with its point turnedbackward, fig. 267, 10. When the muscles draw forward theexternal pterygoid, the maxillary bone is pushed forward, and therecumbent fang withdrawn from its concealment and erected. In this power of changing the direction of a large tooth, so thatit may not impede the passage of food through the mouth, we mayperceive an analogy between the viper and the Lophius; but inthe fish the movement is confined to the tooth alone, and is de-pendent on the mere physical property of the elastic medium ofattachment; in the serpent the tooth has no independent motion,but rotates with the jaw, whose movements are governed bymuscular actions. In the fish the great teeth are erect, exceptwhen pressed down by some extraneous force. In the serpentthe habitual position of the fang is the recumbent
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Keywords: ., bookcentury1800, booksubject, booksubjectbirds, booksubjectfishes
