144 GENERAL SYSTEMATIC BACTERIOLOGY 



or siibspeoiiic njuuo. oithor as valid iiamo or synonym, that species or subspecies 

 beci>nies i^K^o facto type of the genus. (IVpe by nbsolute tautonymy.) 



II. Cases in which the generic type is accepted not solely upon basis of the 

 original publicat ion : 



e. The following species are excluded front consideration in ileterniining the 

 types of genera. 



a. Species which were not included vuvder the generic name at the time of its 

 original publication. 



/S. Species which were special ituiuirendae from the standpoint of the author 

 of the generic name at the time of its publication. 



-). Species which the author of the genus doubtfully referred to it. 



f. In case a generic name without origitially designated type is proposed as a 

 substitute for another generic name, with or without type, the type of either, 

 when established, becomes ii\<o fado type of other. 



g. If an author, in publishing a genus with more than one valid species, fails to 

 designate (.see a^ or to indicate (.see b, d"* its type, any subsequent author may 

 select the type, and such designation is not subject to change. (.Type by subse- 

 quent ilesignatioit."* 



The meaning of the expression ''select the type" is to be rigidly construed. 

 Mention of a species as an illustration or example of a genus does not constitute 

 a selection of a type. 



III. Recommendations. In selecting types by subsequent designation, authors 

 will do well to govern themselves by the following recommendations: 



h. In case of Linnaean genera, select as type the most common or the medicinal 

 species. (^Liunaean rule, 1751. ) 



1. If a genus, without designated type, contains among its original species one 

 possessing as a specific or subspocitic name, either as valid name or synonyni, a 

 name which is virtually the same as the generic nan\e. or of the same origin or 

 same meaning, preference should be shown to that species in designating the type, 

 unless such prefertMice is strongly contraindicated by other factors. (.Tjpe by 

 virtual tautonymy.) Examples: Bos taurus, Equus caballus. Oris aries. Scomber 

 scombri!^, Sphaerostoma glohiporum; contraindicated in Dipetalonen.a (compare 

 species Filaria dipetata, of which only one sex was described, based upon one 

 specimen and not studieil in detaiP. 



j. If the genus contains both exotic and nonexotie species from the standpoint 

 of the original author, the type should be selected from the nonexotie species. 



k. If some of the original species have later been classitied in other genera, 

 preference should be shown to the species still remaining in the original genus. 

 (TyiH> by elimination.) 



1. Species based upon sexually mature specimens should take precedence over 

 sjH^cies based upon larval or immature forms. 



m. Show pivference to species bearing the name conimunis, vulgaris, rnedicina- 

 lis, or officinalis. 



n. Show preference to the best described, best figured, best known, or most 

 easily obtainable species, or to one of which a type specimen can be obtained. 



o. Show preference to a species which belongs to a group containing as large a 

 number of the species as possible. (.De Candolle's rule. ) 



p. In parasitic genera, select, if possible, a species which occurs in the man or 

 some food animal or in some very common and widespread host species. 



