18 MINOT ON THE TONGUE 



VI. Summary. 



I give a brief summary of the anatomy of the snake's tongue. It is long and cylindri- 

 cal, tapering Jjehind, forked in front. Its anterior portion can be retracted within a 

 sheath, which opens on the floor of the mouth in front of the glottis. The upper surface 

 upon the front half of the free part of the tongue, is somewhat expanded and flattened, 

 and is separated from the lower surface by a shallow longitudinal furrow, which faces 

 downwards. The epithelium of the mouth is continuous with that of the sheath and of 

 the tongue. The lingual epithelium is stratified and has a follicular structure on the ante- 

 rior part of the tongue, where it is also much thickened, and further characterized by con- 

 taining cells with peculiar clear nuclei. Upon the front half of the free segment of the 

 tongue, the epithelium is thickened along nine longitudinal lines, three dorsal, two on the 

 furrows, and two on each side below the furrows. The tongue receives three pairs of 

 nerves ; the anterior, probably the Ungualis tr'ujemini, goes first to the sheath, in the 

 walls of which it runs backwards, being finally distributed to the (tip of the tongue); 

 the middle enters the attached portion of the tongue and is. distributed to the sides of 

 the tongue (?); the third jiair, the hypoglossals, enters at the posterior extremity of the 

 tongue, and send, each, a larger branch forwards in the midst of the ceratoglossus muscle 

 within the tongue, and a smaller liranch Ijackwards along the outside of the same muscles. 

 The muscles of the tongue are five, three single, and two paired, of which one pair only, 

 the ceratoglossi, arise extrinsically. The ceratoglossi take their origin from the posterior 

 ends of the hyoid cornu, run straight forward into and through the body of the tongue 

 along the under half, and enter the tips. There is a dorsal longitudinal muscle, the Un- 

 gualis, confined to the free part of the tongue. A median verticalis divides the tongue 

 into symmetrical halves, right and left. There are three transverse muscles, one supe- 

 rior lying above the ceratoglossi, and, in the free part of the tongue, heloio the Ungualis. 

 The iransversi inferiores may he considered parts of one muscle. The transverse muscles 

 and the vertical are all distinctly separated in the posterior part of their tongue, but 

 anteriorly their fibres interlace in a very complicated manner. All the muscles are united 

 to form the fleshy core of the tongue, and are encased in a common fascia. At the fork, 

 the core also divides to furnish a core for each tip. The muscular core is separated from 

 the epithelium of the tongue by highly vascular adenoid tissue. Two nerves lie in the 

 midst of the muscles, the hypoglossiis in the ceratoglossns, the Ungualis (?) in the irans- 

 versus superior. The third nerve, the glossopharyngeus (?), lies in the adenoid tissue at 

 the side of the core. 



The tongue of Ameiva closely resembles that of the snakes, being forked in front ; it 

 differs principally in having scales above, and two peculiar scales underneath, at the base 

 of each tip. Its upper surface is expanded and separated from the lower surface by a 

 longitudinal furrow. In sections the muscles are seen to be precisely the same in num- 

 ber and general disposition as in corresponding sections from the snake, the differences 

 being only of proportions and in details. [Cf. figs. 8 and 12.) 



The tongue of the Chamaeleon is constructed upon another type altogether, and its 

 muscles cannot at present be homologized with those of Ancistrodon and Ameiva. There 

 are three pairs of longitudinal muscles, one pair resembling the iransversi inferiores of 



