LEADING GROUPS OF EXISTING SYSTEMS 163 



of branches nor of classes; let us now examine further whether it is a 

 character of species. A rapid review of some of the best known types 

 of the animal kingdom, embracing well-defined genera with many 

 species, will at once show that this cannot be the case, for such species 

 do not generally show the least difference in their forms. Neither the 

 many species of Squirrels, nor the true Mice, nor the Weasels, nor the 

 Bears, nor the Eagles, nor the Falcons, nor the Sparrows, nor the 

 Warblers, nor the genuine Woodpeckers, nor the true Lizards, nor 

 the Frogs, nor the Toads, nor the Skates, nor the Sharks proper, nor 

 the Turbots, nor the Soles, nor the Eels, nor the Mackerels, nor the 

 Sculpins, nor the genuine Shrimps, nor the Crawfishes, nor the Hawk- 

 moths, nor the Geometers, nor the Dorbugs, nor the Spring-Beetles, 

 nor the Tapeworms, nor the Cuttlefishes, nor the Slugs, nor the true 

 Asterias, nor the Sea-Anemones could be distinguished among them- 

 selves, one from the other, by their form only. There may be differ- 

 ences in the proportions of some of their parts, but the pattern of 

 every species belonging to well-defined natural genera is so com- 

 pletely identical that it will never afford specific characters. There 

 are genera in our system which, as they now stand, might be alluded 

 to as examples contrary to this statement; but such genera are still 

 based upon very questionable features and are likely to be found 

 in the end to consist of unnatural associations of heterogeneous 

 species: at all events, all recent improvements in Zoology have gone 

 to limit genera gradually more and more in such a manner that 

 the species belonging to each have shown successively less and less 

 difference in form, until they have assumed in that respect the most 

 homogeneous appearance. Are natural genera any more to be dis- 

 tinguished by their form one from the other? Is there any appreciable 

 difference in the general form? I say purposely general form, because 

 a more or less prominent nose, larger or smaller ears, longer or 

 shorter claws, etc., do not essentially modify the form. Is there any 

 real difference in the general form between the genera of the most 

 natural families? Do, for instance, the genera of Ursina, the Bears, 

 the Badger, the Wolverines, the Raccoons, differ in form? Do the 

 Phocoidae, the Delphinoidas, the Falconinse, the Turdinae, the Frin- 

 gillinse, the Picinse, the Scolopacinae, the Chelonioidae, the Geckonina, 

 the Colubrina, the Sparoidas, the Elateridas, the Pyralidoidas, the 

 Echinoidae, etc., differ any more among themselves? Certainly not; 



