38 CLASSIFICATION OF FISHES. 



ment of the scales which form the lateral line, more es- 

 pecially towards the end of the tail, where, in some in- 

 stances, they hecome analogous to those carinated plates 

 so conspicuous in Caranx, and still more so in the 

 GasterostidcB or sticklehacks, a structure which beauti- 

 fully illustrates the analogy of all these fishes to the 

 gurnards. 



(37.) Leaving the Zeince by means of the genus 

 Equula Cuv., and some other kindred forms, we enter 

 among the true Centronotin^, or spine-backs, the dis- 

 tinguishing character of which is seen in their lengthened 

 fusiform body ; totally different from that of the Zeince, 

 both as to form and thickness. Nearly all are covered 

 with conspicuous scales, and armed with short sharp 

 spines, placed before their dorsal fin, either erect or point- 

 ing forwards on their backs. It is here we place the genus 

 Siganus of Forskill (^Amphicanthus of Cuv.), on account 

 of its possessing a recumbent spine, and from its close 

 resemblance to Psenes, this last conducting us to the 

 genus Seriola, which contains several sub-genera ; as 

 a whole, however, it is well distinguished, by having the 

 dorsal spines so united as to form a second dorsal fin, 

 perfectly separated from the hinder one. This group is 

 beautifully connected to that of Centronotus (the type 

 of the whole sub-family), by Nomeus, which unites 

 most perfectly to Naucrates, a name given by Rafinesque 

 to the celebrated pilot fish ; and one of the very few 

 of this author that has been adopted by Cuvier. Re- 

 garding these interesting fish, it will be seen, in the 

 appendix, that two, if not three species, exist in the 

 Mediterranean, unknown! to Cuvier and Valenciennes. 

 How far the fact is correct, of these fish being guides to 

 the sharks, it is really difficult, if not impossible, to de- 

 termine. It is contrary to aU we know of nature, to 

 suppose that the subsistence of one animal depends upon 

 the guidance of another, or that every being is not 

 endowed with those faculties necessary for its perception 

 of danger, or for the procurance of its food ; and yet 

 several anecdotes, recorded by observing naturalists, very 



