ALIMENTARY CANAL OF REPTILES. 



437 



retracted, fig. 297, a and C, is almost wholly supported thereby, 

 and, when withdrawn, the cavity of the sheath is occupied by 

 a ductile cellulosity. The bulbous end of the tongue, fig. 296, 

 and fig. 297, a, b, is divided by a transverse curved groove into 

 a shorter upper, ib. a, and a longer lower lobe, ib. d, resembling the 

 prehensile part of the Elephant's proboscis ; the surface is finely 

 rugous, and bedewed by adhesive secretion. Between the bulb 

 and the base the glossohyal sheath is immediately surrounded by 

 fibrous, degenerating into lax elastic, tissue, covered by the lingual 

 skin, which is thrown into circular rugae or rings, in the contracted 

 state (as in fig. 297, a, b, and in c, where this part of the tongue 

 is exposed by divaricating the geniohyoid muscles, c). The tissue 

 of the glossohyal sheath consists chiefly of unstriped muscular fibres, 

 arranged transversely. The longitudinal fibres are those of a pair 

 of ' glossohyoidei,' extending along the sides of the annular exten- 

 sile part, and spreading out at the bulbous part, of the tongue. 

 The circular fibres, strongly contracting, diminish the thickness, 

 increase the length, and, squeezing the smooth supporting style, slip 

 off the elongated part of the tongue from its fore part with a certain 



297 



Tongue of the Chameleon, ccxl. 



jerk. But with this action is associated a more powerful propeller 

 of the weighted bulbous end of the tongue, exercised by the 

 muscles of its bony support. The geniohyoidei, fig. c, c, and a, e, 



