xvi THE HISTORY OF ZOOLOGY 633 



in a definite and uniform way, with due subordination of one 

 to the other ; it was he who invented binomial nomenclature, 

 the advantage of which in promoting precision in systematic 

 work it is impossible to over-estimate. He gave each species 

 <i brief diagnosis in Latin, so that any naturalist versed in his 

 system could recognise whether an animal or plant which came 

 under his notice was already described or not. In this way he, as 

 it were, pigeon-holed the facts of Biology, and so made the deter- 

 mination of the proper place of any new fact a comparatively 

 simple matter. By universal consent, the Systema Natures is 

 taken as a starting point by systematists. It is customary to 

 place after the name of a species the initial or abbreviated name 

 of the writer by whom the species was first distinguished and 

 named. For instance, the Bass, a common British Teleost, was 

 named Perca labrax by Linnaeus. In 1828, Cuvier and 

 Valenciennes, in their great work on Fishes, recognised that it 

 was geiierically distinct from the Perch, and, retaining the generic 

 name Perca for the latter, called the Bass Labrax lupus. In 1860, 

 further investigations into the Perch family necessitated placing 

 it in the genus Morone, and, according to the law of priority, the 

 specific name lupus gives place to labrax, the latter having been 

 applied by Linnaeus. The Bass is therefore correctly called 

 Morone labrax, Linn., the more usual name, Labrax lupus, Cuv. and 

 Val. becoming a synonym. In deciding all such questions of 

 priority, the tenth edition (1758) of the Systema Natural is taken 

 as a starting point : all species distinguished by Linnaeus, and 

 not subsequently split up into two or more species, are dis- 

 tinguished by the abbreviation L. or Linn. For instance, Canis 

 familiaris Linn, is the Domestic Dog, Passer domesticus Linn. 

 the House Sparrow : and names given by the older naturalists are 

 neglected unless endorsed by Linnaeus. 



In many respects the system of Linnaeus was eminently artificial ; 

 lie relied too much on single characters in classification, and did 

 not take the totality of structure into sufficient consideration. He 

 divided the animal kingdom into the following six classes : 



1. Mammalia. 



2. Aves 



3. Amphibia [including Reptilia and Amphibia], 



4. Pisces. 



5. Insecta [including all the Arthropoda]. 



6. Vermes [including Mollusca, Worms, Echinoderms, Coslen- 



terata, and Protozoa]. 



It will be seen that all these classes are natural groups, with 

 the exception of the last, but that they are far from being of even 

 approximately equal value. The first four are what we still call 

 classes, but there is no attempt to unite them into a single group 

 -of higher order ; and in this respect the classification of Linnaeus 



