Chap. U. FAMILY CHARACTERS. 189 



highest importance to remember that the independence of any natural group in 

 the animal kingdom can in no way be determined by the numljer of its repre- 

 sentatives. The Squirrels and Mice are very numerous in comparison to the 

 different fsimilies of Edentata or of Pachyderms ; the Warblers or Herons are very 

 numerous in comparison to the Ostriches or Pelicans ; the Snakes and Lizards are 

 very numerous in comparison to the Turtles or Toads ; the Perches, the Mackerels, 

 and the Suckers are very numerous in comparison to the Sharks and Skates, etc. 

 But all the natural groups founded uj^on a knowledge of many of them are no 

 more natural than if their existence had been ascertained from a careful exami- 

 nation of a single representative of each. The history of our science affords ample 

 evidence to substantiate this assertion. The genus Esox, as limited by Linnaeus, 

 contains nine species, every one of which is now referred to a distinct genus : 

 Esox Lucius has become the type of the genus Esox proper ; Esox Belone, the type 

 of the genus Belone ; Esox IrasiUensis, the type of the genus HemirhampJms : Esox 

 VuljH's belongs to the genus Butirinus ; Esox Si/nodus, to the genus Satiriis ; Esox 

 Hepsclus, to the genus EngrauUs^ ; Esox gi/mnocepJialus, to the genus Enjtlmnus : Esox 

 Sphi/rcena has become the type of the genus Splvjrcena ; and Esox osscus, the type 

 of the genus Lepidosteus. These nine genera are referred by some ichthyologists 

 to four different families, and by others to eight distinct fiimilies. Now, if either 

 Linnasus or Artedi had carefully studied the species in their tinae referred to the 

 genus Esox, they might have recognized the different genera to which they were 

 afterwards referred, quite as well as Lacepede or Cuvier, or any other ichthy- 

 ologist ; and they might even have perceived the necessity of separating some of 

 them more widely than they were in the days of Cuvier, since, as I have shown, 

 Lepidosteus differs greatly from all the other living fishes. 



But, to come to the point I am aiming at. The genera Belone, Hemirhamphus, 

 Saurus, Engraulis, Butirinus, Erythrinus, SphyriBna, and Lepidosteus, could as truly 

 have been separated from Esox by Linnaeus with the aid of that one species he 

 knew of each, as they can be characterized now that we know many species of 

 all of them ; and, iipon a discriminating discussion of their diflferences, they might 

 have lieen characterized, not only in the same way as they are now in most works, 

 but even with greater precision. What is needed for such systematic work is 

 accurate knowledge of the annuals before us, and not a large number of species; 

 though it is true that we derive additional aid, and our task is made comparatively 

 easy, when we become acquainted with many closely allied species, leading, by 

 their near affinity, to a readier perception of their generic relations. 



' I do not mean to enter here into a critical Esox, which have also led to extensive discussions 

 controversy as to the true atRnities of this species, among ichthyologists : for my purpose, one view 

 nor of two other Linna'au species of the genus of the case is as acceptable as another. 



