ALIMENTAHY CANAL OF FISHES. 411 



Mammals : nor does the skin, continued from the lip over the jaw, 

 show so well the character of the ( gum.' Many Fishes, especially 

 those of the Cyprinoid, Mugiloid, and Siluroid families, have 

 fleshy and sensitive labial barbs or cirri ; those of the Siluroids 

 being supported by bony or gristly stems. Tentacles depend 

 from the rostral prolongation of the Sturgeon, and from the man- 

 dibular symphysis of the Cod. The Lepidosiren and Cod have 

 fringed processes or filaments between the teeth and lips, which 

 seem designed to assist in testing and selecting the food. 1 The 

 lips of most Sharks and Rays are partially supported by labial 

 cartilages. 



The edentulous Sturgeon is compensated by a produced cartila- 

 ginous snout, with which it upturns the mud in quest of food at 

 the bottom of the rivers it frequents. The allied Spatularia, in 

 which a minutely shagreened surface on the jaws represents the 

 whole dental system, has had the force of dev elopement of subsi- 

 diary organs of alimentation expended in the production of the 

 still more remarkable rostrum, fig. 276, ?/, which is broad and flat, 

 like the mandible of a spoonbill, and is more than half the length 

 of the entire body. Other modifications and actions of the mouth 

 Ijave been noticed in the description of the jaws. 



The conical lip of the suctorial Myxinoids, fig. 248, sends off 

 from its anterior expanded border six or eight long tentacula : this 

 border is fringed by numerous cirri in the Lamprey, fig. 277, the 

 inner surface of the lips is beset with short branched tentacles in 

 the Ammocete : the Lancelet has more simple, but highly vascular 

 intra-buccal processes, fig. 169, </, g, and the vertically fissured 

 aperture of its mouth is provided on each side with a series of 

 long slender jointed and ciliated tentacula, ib.y,y, which mainly 

 tend, by the perpetual vortex they cause in the surrounding 

 water, to bring the animalcular nutriment within the grasp of the 

 pharynx, ph, the orifice of which is also surrounded by vibratile 

 cilia. 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 glossohyal, when it projects at all into the mouth, as 

 in fig. 276, c, is rarely covered by integuments so organised as to 

 suggest their being endowed with the sense of taste. In Anguil- 

 lidce the lingual membrane is raised by some adipose and muscular 



1 Mr. Couch narrates an instance of a large Cod, in good condition, taken on a 

 line at Polperro, Cornwall, in which the orbits contained no eyeballs, but were covered 

 with an opake reticulated skin. So that he felt convinced that ' eyes never had 

 existed ;' yet the fish was in good condition, and must have depended on the tactile 

 organs about the mouth for the discovery of its food. xcvm. p. 72. 



