412 



ANATOMY OF VERTEBRATES. 



tissue. But the surface of the prominent tongue is generally 

 callous, and either smooth and devoid of papilhis, or, if the repre- 



277 



Vertical scrtidu of iinaitli, Lniiijn-ey. v. 



sentatives of these be jiresent, they are calcifiod and the tongue is 

 beset with teeth. It, then, seizes and ]iasses the food on to the 

 gullet; but the supporting arch of the tongue, fig. 85, .38-40, works 

 chiefly for respiratory purposes. In the Lamprey, the tongue, fig. 

 277, d, is more exclusively related to the digestive function than 

 in higher Fishes : it can be protruded and retracted, like a piston, 

 when the sucker is attached to the prey ; and it is armed by small 

 serrate teeth for tearing the flesh. In a few Fishes the integu- 

 ment of the palate presents that degree of vascularity and supply 

 of nerves which indicates some selective sense, analogous to taste. 

 In the Cyprinoids tlie palate is cushioned with a thick soft 

 vascular substance, exuding mucus by numerous minute pores, 

 but more remarkable for its irritable erectile or contractile 

 property : ' if any part of this Ijc pricked in a live Carp, the part 

 rises immediately into a cone, which slowly subsides ; this peculiar 

 tissue is richly supplied by branches of the glosso-pharyngeal 

 nerves : it may assist in the rcrpiisitc movements of the vegetable 

 food, as well as add to it an animalising and solvent mucus, whilst 

 it is undergoing mastication by the ])haryngeal teeth. In the 

 Gymnotus there are four scries of Ijranehed fleshy processes in the 

 mouth, one upon the dorsum of the tongue, a second depending 

 from the palate, and one along each side of the mouth. 



■ The only representatives of a salivary system in Fishes are the 

 mucous follicles that communicate with tlic mouth.^ The chief of 



2 Tho reddish vascular body, discovered by Kelzius (cxxi.) between the basi- 



