In order to keep the system of definite scientific names workable, the 

 International Zoological Congress has established (1889 to the present) a set 

 of rules governing the names of species, genera and families of animals. Any 

 question concerning the proper use of these names is referred to a committee 

 of this Congress. The most important rule established by the code is the sO' 

 called Law of Priority. The animal names used in the tenth edition of 

 Linnaeus' Systema J\laturae (1758) are accepted as the starting point. Any 

 animal not therein described is called by the name first applied to it since, 

 provided the describer followed the Linnaean system and published the name 

 and description in an acceptable manner. Unfortunately many of the early 

 scientists did not have access to the publications of others and some of them 

 made their descriptions quite vague, so that frequently several names have 

 been applied to the same animal. In that case the first scientific name properly 

 given is accepted as the true scientific name, the later ones being called 

 synonyms. 



A few other rules should be kept in mind. The name of the genus is 

 always capitalized. In animal names, although not in plant names, the name 

 of the species should never be capitalized. A name once used as the generic 

 name of an animal must never be used for any other animal. The latter 

 regulation does not apply to the names of species. 



In order to enable one to refer to the original description and to check 

 on errors, the name of the describer (called the author) is frequently written 

 after the scientific name without intervening punctuation, as Homo sapiens 

 Linnaeus. If for any reason it has been necessary to change the generic name, 

 the name of the author of the species is bracketed. Thus the clam originally 

 described as Unio ovata Say is now known as Lampsilis ovata (Say). Oc' 

 casionally one finds three names instead of two, as Microtus montanus ar-izoneri' 

 Sis Bailey. This means that the species has been further subdivided into sub' 

 species, one of which, arizonensis, was first properly named and described by 

 Bailey. 



Identification is not always easy. Our divisions into phyla, classes and 

 orders are arbitrary and each group includes a number of animals that do not 

 possess all the structures regarded as characteristic of that group. Among 

 the microscopic organisms there are several, such as Euglena and Volvox, that 

 cannot be definitely assigned to the animal or to the plant kingdom. Many 

 colonial protozoans can be told only with difficulty from higher forms, the 

 usual distinction being that in the protozoan colony there is no specialization 

 among the somatic or body cells, such specialization being the rule in the bodies 

 of the higher animals. In our pond life the small annelid worms and the larvae 

 of insects look much alike, the presence of distinct mouth parts and of a definite 

 head usually distinguishing the latter. Even some vertebrates may be con' 

 fused with invertebrates at first sight. Some of the degenerate, burrowing 



