230 LECTURE IX. 



and ciliated tentacula, {ib.f,f), which mainly tend, by the per- 

 petual vortex they cavise in the surrounding water, to bring the ani- 

 malcular nutriment within the grasp of the pharynx {ph). There 

 is no tongue in this rudimentary fish ; that organ is often absent or 

 very small in the typical members of the Class ; its basis, the glosso- 

 hyal, when it projects at all into the mouth, as mjig. 61. c, is rarely 

 covered by integuments so organised as to suggest their being en- 

 dowed with the sense of taste ; they are generally callous, and either 

 smooth and devoid of papillte, or, if the representatives of these be 

 present, they are calcified and the tongue is beset with teeth. The 

 integuments of the palate, however, not unfrequently present that 

 degree of vascularity and supply of nerves which indicate some 

 selective sense, analogous to taste. In the Cyprinoids the 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 you prick any part of this 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 requisite movements of the vegetable 

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

 it is undergoing mastication by the pharyngeal teeth. In the Gym- 

 notus there are four series of branched 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 reddish vas- 

 cular body, discovered by Retzius f between the basi-branchials and the 

 sterno-hyoid muscles in Cartilaginous Fishes, and which exists also in 

 Gadus, Salmo, and some other Osseous Fishes, has been compared 

 to a sublingual salivary gland : but it is a ' vaso-ganglion ; ' and its 

 homology with the thyroid, indicated by Mr. Simon \, is a truer view 

 of its nature. The only other representatives of a salivary system in 

 Fishes are the mucous follicles that communicate with the mouth. 

 There are neither tonsils nor velum palati in Fishes : the folds of 

 membrane behind the upper and lower jaws, of which 'internal lips ' 

 the Sword-fish and Dory afford good examples, seem intended to 

 prevent the reflux of the respiratory streams of water rather than the 

 escape of food from the mouth. In the Lepidosiren these folds or 

 inner lips are papillose and glandular. 



In the aberrant Dertnopteri and Plagiostomi, at the two ex- 

 tremes of the Class, in which there are numerous branchial apertures 

 on each side, and the respiratory streams do not necessarily enter by 

 the mouth, the last pair of branchial arches are not metamorphosed 

 into pharyngeal jaws, and the entry to the gullet is simply constricted 



* xcix. f cxix. I cxvi. p. 300. 



