BORER. 413 



acute tlie fixcultics of smell and taste, and perhaps in directing 

 the inhaled current of water. At the hindmost half of the 

 gullet there are six small openings, regularly arranged on each 

 side, which communicate each by a tube with an equal numbel 

 of membranous vesicles, a little compressed, and of the diameter 

 of the fifth or sixth of an inch, the lining of each of which 

 forms considerable folds, which sei've in the place of gill-plates 

 for performing the function of breathing; the water passing 

 from the gullet through these tubes to the vesicles or gills, 

 and from them, on each side by passages uniting into a tube, 

 the water is discharged by a couple of openings, close to each 

 other on the belly; and Avhich therefore ai'c truly the breathing 

 holes or external gills, and taken as a whole nothing can be 

 more wisely contrived for keeping in store and supplying the 

 necessary fluid in a creature which occasionally for a long time 

 cannot obtain a renewal of the same from without. These 

 outward openings of the breathing organs are behind the muscular 

 apparatus of the tongue, which is large and turned far backward, 

 reaching from the girllet to the openings, and in thickness is 

 equal to half the diameter of the body; its action being directed 

 by several powerful muscles, which, with the help of the grating 

 teeth, will act on the food like a file, while the single tooth 

 on the palate is employed in fixing the mouth of the devourer 

 on its prey; a structure and action not much unlike what is 

 common in a large portion of osseous fishes. 



Mr. Owen remarks that the whole of the anterior parts, as 

 the muscles and integuments of the head, the barbs, nasal tube, 

 membrane lining the mouth and tongue, and the teeth in 

 the throat, with the pharynx or passage leading to the gullet, 

 are furnished with one common nerve, termed the fifth pair, 

 from which they obtain a high degree of sensation of a peculiar 

 kind. And singular, as well as effectual, as this inward orga- 

 nization appears to be for the special habits of this fish, the 

 structure of the spine seems scarcely less so as compared with 

 that of other fishes, but as such suggesting an opinion of a 

 very low degree of intelligence. Connected with this Dr. 

 Eoget observes, in his Bridgewater Treatise, — "There are few 

 parts in the structure of animals that exhibit more remarkable 

 instances of the law of gradation than the spine of fishes, in 

 which we may trace a regular progression of development, 



