DETERMINATION OF GENERIC TYPES, ETC. 39 



First, he might rule by page precedence that redivwum is the type. 

 In this instance he would have to take Chaos, 1767, into consideration 

 as competitive with Anguillula, 1786; or 



Second, he might rule by elimination that since redivivum has been 

 transferred to Anguillula and since protJieus = chaos is type of Amiba, 

 the type of Chaos should be selected from fungorum, ustilago, and 

 infusorium. See, however, the Linnsean rule, p. 64. 



6. TYPE BY VIRTUAL TAUTONYMY. 



RECOMMENDATION. If a genus, without designated type, contains among 

 its original species one possessing as specific or subspeciflc name, either as 

 valid name or synonym, a name which is virtually the same as the generic 

 name, or of the same origin or same meaning, preference should be shown to 

 that species in designating the type, unless such preference is strongly con- 

 traindicated by other factors. 



Under type by absolute tautonymy are here classified such cases in 

 which the generic and specific names are literatim identical. Under 

 type by virtual tautonymy are here included those cases in which the 

 specific name is taken as basis for the generic name, or vice versa. 



It must be admitted that the latter cases are not always entirely free 

 from individual interpretation, but the following cases mentioned in 

 this paper seem to admit of no doubt: 



Capillaria Zeder, 1800; capillaris Rudolphi, 1809. 



Trichuris Roederer & Wagler, 1761; trichiura Linnaeus, 1771; also monotypical. 



Viscosia de Man, 1890; viscosus Bastian, 1865 [de Man has written us that he based 



the name Viscosia upon the name viscosus and that the latter should be taken 



as type of the former]. 



Next comes a class of cases in regard to which it seems to us equally 

 clear what should be done, but opinion will doubtless differ among 

 various authors. Reference is made to cases in which two different 

 words with identical or practically identical meaning are used as 

 generic and specific names. Such cases are often the result of a dislike 

 on the part of many authors to the use of tautonymic combinations. 

 Two instances of this class occur in the present paper. 



Echinocephalus Molin, 1858; uncinatus Molin, 1858; also type because it is the only 



original valid species, see p. 29. 

 Heterochdlus Diesing, 1839; heterolobus Diesing, 1838tunicatus Diesing, 1839; also 



monotypical. 



As there are other grounds besides virtual tautonymy for selecting 

 uncinatus&nd heterolobus as types of J&hmocephalusand Ileteroeheilus, 

 respectively, no author can vaiidly object to using virtual tautonymy 

 as additional reason for such selection. 



As other instances of what are considered type by virtual tautonymy, 

 may be mentioned: Bos taurus, Sphserostoma globiporum, Copra 

 hircus, Equus cahallus, Ovis aries, .Scomber scombrus, Sus scrofa, or 

 Sus porous. 



