1911] Composition of Taxonomic Papers 199 



What constitutes a genus? A single species or several that, 

 aside of specific differences, have certain morphological features 

 in common, which distinguish them from all other groups of 

 species. 



When is a genus valid? When so stated by the sponsor, 

 the nomenclator having noted certain morphological characters, 

 the value of which is recognized by fellow-workers, and who 

 accept this diagnosis upon the given characters; when placed 

 with a monomial (specific) to signify that the species possesses 

 certain distinguishing group characters. 



As genera constitute the lowest, but at the same time the 

 most important, phase of grouping, at least some attention 

 should be given to the formation of generic descriptions; espec- 

 ially so in larger contributions, such as monographs and generic 

 summaries and synopses. Generic description is allied to speci- 

 fic description; hence methods ought to be similar. 



Some of the essentials of a generic description are the 

 following : 



1. That the type species be cited. It should be noted that the 

 type species must be a species then or previously described; else we 

 have merely a nude name. 



2. That the characters on which the species is based be given. 

 Although the generic name alone, when coupled with a described spe- 

 cies, is recognized as valid by the codes, the systematist will insist that 

 the absence of a generic description is an unfair apprisal on the part of 

 the nomenclator. 



3. That these characters be stated concisely; that is, write to the 

 point. Brevity is not conciseness. One may be brief and vague at 

 the same time. 



4. That these characters be stated in orderly manner. Especially 

 in larger papers unity of methods is advantageous. If one description 

 begins with the legs, another with head, a third with the venation, etc., 

 study is made difficult. Uniformity of methods facilitates study and 

 progress. 



5. That other species belonging to the new genus be listed. While 

 this necessitates thorough study on the part of the nomenclator, it 

 really is his duty. To split up large genera upon characters drawn 

 from a single species is a simple matter. But the nomenclator should 

 verify the stability of his characters by extensive comparison with 

 related species. 



6. That other genera be compared, or, at least, the position of the 

 new genus indicated. To describe a new genus of a family already 

 containing twenty or thirty genera and not indicate the position or 

 relations of the newcomer, is not scientific; it denotes carelessness or 

 ignorance. 



