Page:Natural History, Reptiles.djvu/159

Rh of hard cement, and penetrate the dorsal (upper) parietes of the œsophagus: they may be readily seen even in very young subjects, and in the interior of that tube, in which their points are directed backwards. The shell being sawed open longitudinally by these vertebral teeth, the egg is crushed by the contractions of the gullet, and is carried to the stomach, where the shell is no doubt soon dissolved by the gastric juice.”

The tongue in this Order is slender, and divided into two long and pointed filaments, which are capable of being entirely retracted within a sheath, or of being protruded from the mouth, with great swiftness of motion. Serpents are said to be enabled to lap up fluids with this forked tongue, which, however, seems to be ill suited for such an operation. The vulgar notion which associates a hurtful power with the tongue, often spoken of as the “sting,” is entirely erroneous.

The mode in which respiration is performed is described by MM. Duméril and Bibron to be as follows:–“The glottis, which has two lips, and represents a very simple larynx, opens in the mouth beneath the sheath of the tongue; by means of the muscles of the os hyoïdes [or bone of the tongue], which push it, it is raised so as to be presented in a dilated state behind the back nostrils. The vacuum caused by the action of the ribs in the belly tends to dilate the lung, which through the medium of the trachea, immediately admits the air which is introduced during an inspiration: this is slow, continuing for some