24 BUREAU OF ANIMAL INDUSTRY. 



b. Select as type some species which the original author studied personally, unless 

 it can be definitely shown that he had some other species more particularly in mind. 



c. If the original genus has already been divided without designation of type, the 

 type should be restricted by elimination, namely, by successively rejecting all the 

 species which have already been transferred to other genera; the type is then 

 selected from the species which remain. 



If the genus contains both exotic and nonexotic species, from the standpoint of 

 the original author, the type is to be selected from the nonexotic species. 



d. Select as type the species which is best described, or best figured, or best 

 known. 



AXIOMS RELATIVE TO TYPE SPECIES. 



In determining the type species of a genus, it is self-evident that 

 such determination should be made in accordance with the original 

 intentions of the original author of the genus, provided his intentions 

 can be definitely recognized. 



Not only is this proposition in harmony with the spirit of the law 

 of priority, but it has its very practical application, namely, the more 

 closely it is possible to restrict the determination of a type species to 

 the original paper in which the genus was published, the less litera- 

 ture one has to consider and the fewer will be the divergent views 

 which must be discussed. A blind adoption of the rule of "page 

 precedence" (see pp. 62-63) would permit a determination of all types 

 upon basis of the first generic publication, and, radical as the rule is, 

 it must be -admitted, even by those of us who do not believe in it, that 

 it has much in its favor and that it is possibly still an open question 

 as to whether it leads to greater inconvenience or even to greater 

 absurdities than do certain other rules. 



As a second axiom it may be stated that, according to the spirit of 

 the law of priority, the historical method should be adhered to in case 

 the type can not be determined upon basis of the first publication. 

 Thus, if any author has determined a type for a genus without pre- 

 viously determined type, such determination holds unless it can be 

 shown that it is objectively erroneous. 



RULES AND RECOMMENDATIONS CONCERNING TYPES. 



In the following discussion, the rules and recommendations formu- 

 lated for determining types of genera are based upon the practices 

 now in existence and upon our own experience. It is not maintained 

 that the points discussed cover all cases or that all points exclude a 

 difference of opinion. It is, however, believed that the suggestions 

 made are more in detail than are those usually found in existing codes, 

 and it is hoped that they will be of use either in stimulating further 

 study on the subject, or in serving as a guide to those systematists who 

 have heretofore paid little or no attention to the subject discussed. 



