PREFACE 



American zoological writers who have published books or scientific papers during the 

 past decade show little uniformity in their reference to larger groups of animals. Of 

 course no zoologist wishes to be limited in the choice of names which seem to be most 

 appropriate ; no one wishes to have imposed on him terms which he is ordered to use ; and 

 none desires to have nomenclature become fixed and inflexible. Of all the rewards that 

 Science gives to her retainers those most prized and enjoyed are independence and the 

 right to change old dogmas as soon as the discovery of new truths makes them illogical. 

 Yet because the species of animals now number several hundreds of thousands, the 

 sorting of species into groups must necessarily be continually more accurate and critical. 

 Furthermore, there are men who through ignorance, inertia, or bigotry take little or no 

 cognizance of the progress of current scientific evidence and opinion. For example, cer- 

 tain writers of recent textbooks use such old terms as Annulata and Anura when the 

 most thoughtful and competent students of annelids and amphibians agree that Annelida 

 and Salientia are to be preferred. Dr. R. E. Snodgrass, who has recently studied the 

 anatomy of onychophorans in detail, is convinced that these animals cannot be called 

 arthropods because their muscular systems have quite different relations to nervous 

 structures from those which obtain in arthropods. Dr. J. P. Moore does not believe that 

 onychophorans may be included among annelids. There seems to be no alternative but 

 to set off Onychophora as a group by itself. 



Those who know animals and their classifications in detail perhaps may enjoy using 

 various names for the same group and delight in thus displaying their technical knowledge, 

 but a novice who refers to two or three textbooks and finds the same group called by 

 two or three names is greatly confused. In an attempt to bring about greater uniformity 

 and more careful selection in the use of zoological group names the writer was authorized 

 to form an informal committee and to prepare a list of phyla, classes, and orders of 

 animals which would represent current good usage. This action was taken by Section F 

 of the American Association for the Advancement of Science at the Boston Meeting ; 

 December, 1933. 



Since then many persons who appeared to be interested have been consulted. The 

 following gave advice in connection with the groups mentioned : 



Invertebrata : A. H. Clark, B. G. Chitwood, Roy Miner, L. E. Noland, H. S. Pratt, 

 Waldo Schmitt, H. J. Van Cleave. 



Protozoa : L. E. Noland, and forty-odd protozoologists to whom he sent a question- 

 naire. 



Porifera : H. V. Wilson. 



Coelenterata : Elizabeth Dcichtnann (except Zoantharia). 



Aschelminthes : B. G. Chitivood, M. C. Hall. 



Platyhelminthes : E. B. Price. 



Cestoda : G. R. La Rue. 



Nemertea : W. R. Coc. 



Nemathelminthes : B. G. Chitwood, G. Steiner. 



Acanthocephala : H. J. Van Cleave. 



Bryozoa : R. S. Bossier, R. C. Osburn. 



Echinodermata : A. H. Clark, II. I.. Clark. E. Kirk. 



Brachiopoda : G. A. Cooper. 



Enteropneusta : W. E. Ritter. 



Annelida : J. P. Moore, A. L. Treadwell. 



Anthropoda : H. E. Ewing, R. E. Snodgrass. 



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