TAXONOMY 263 



groups according to their systems of organs, as intestinal, muscular, 

 sexual, respiratory, vascular, etc. His other classification was based 

 on the senses. Thus, there were the Dermatozoa (literally, sldn or touch 

 animals), by which he meant the invertebrates; the Glossozoa (literally, 

 tongue animals), the fishes; the Rhinozoa (nose animals) which included 

 the reptiles; the Otozoa (ear animals), or the birds; and another class, 

 which appears to have been called interchangeably the Ophthalmozoa 

 (eye animals) or Thricozoa (hair animals), the mammals. It would be 

 hard to name a set of distinctions less applicable as classification marks 

 than most of these, but Oken did not engage in practical matters. Men- 

 tion may also be made of the systematic work of Pierre Latreille (1762- 

 1833), Johannes Miiller (1801-1858), and Louis Agassiz (1807-1873). 

 Then there was a host of minor systematists the value of whose labors 

 has been diminished by attempts to force their classifications into some 

 numerical system, as for example those who held that the number of 

 orders in each class should be the same as the number of famihes in each 

 order, or the number of genera in each family. The favored number was 

 five in some classifications, less often three, four or seven. ^ 



These early modes of arrangement of animals have been described, 

 not for any value that may attach to them as classifications, but to form 

 a background for the one system that has survived. It should be 

 obvious, from the brief statements made, that most of the plans used were 

 totally unsuited to the requirements which later developments of zoology 

 would have imposed upon them. The system of Linnaeus, however,, 

 was happily capable of being adapted to the demands of the tenets of 

 evolution, and it alone has persisted to the present time. 



The Liimaean System. — That the Linnaean system was rapidly 

 adopted and is now universally employed by zoologists is doubtless due 

 largely to the fact that it introduced a sharply defined grouping, a defi- 

 nite terminology, and brief, clear diagnoses; that it permitted early natu- 

 ralists to group those forms that resembled each other; and that it equally 

 well permitted the classification of forms according to their relationships. 

 As stated above Linnaeus recognized groups of four different values — 

 the class, the order, the genus (plural, genera), and the species (plural, 

 species). To these categories have been added the 'phylum, (plural, 

 phyla) and subphylum (assemblies greater than the class), the subclass, 

 the suborder, the family, the subfamily, the subgenus, the subspecies and 

 others. Of these additional groups the phylum and family are now 

 generally accepted, and the others are used for some groups or by some 

 naturahsts. The rank of recognized categories may be expressed as 

 follows: 



' For many of the facts regarding these old attempts at classification we are in- 

 debted to Theodore N. Gill, Annual Report of the Smithsonian Institution for 1907. 



