DETERMINATION OF GENERIC TYPES, ETC. 59 



(a) Cases in which all of the original species have been selected as 

 types for more recent genera, as, for instance, 



X-us, 1840, with the species; 



albus, type of Y-us, 1845. 

 cinereus t type of Z-us, 1850. 

 niger, type of M-us, 1855. 



In a case of this kind the last species so transferred (niger in the 

 hypothetical case cited) is taken as type of the original genus (X-us), 

 and the new genus (M-us) based upon this species is suppressed as an 

 unconditional synonym. 



(b) In other cases the species which the original author intended as 

 type has been made the type of a new genus. In this instance the 

 original author's intentions should be carried out. One such case is 

 found among nematodes, namely : 



Chromadora Bastian, 1865, contained: 



vulgaris, which de Man took as type for Euchromadora, 1886, and eight other 

 species, none of which appears to have been eliminated. 



De Man's action was unfortunate in this case. By the Linnsean 

 principle of 1751 (see below, p. 64), vulgaris should have had prefer- 

 ence as type of Chromadora, even if de Man was not aware of the 

 fact that Bastian intended this as his type. It seems best in this case 

 to carry out Bastian's intentions of taking vulgaris as his type. 



The general principle of type by elimination, as judged upon the 

 cases of Spiliphera, Theristus^ and the hypothetical case of X-us, just 

 given, might lead one to believe that "type by elimination" is a highly 

 satisfactory method and of easy application. Any author, however, 

 who will attempt to apply the method of "type by elimination" to a 

 large number of genera, and to compare his methods with those of 

 other systematists, will probably agree with us that the method as 

 generally applied is frequently far from satisfactory. In fact, system- 

 atists are by no means agreed as to just what constitutes "elimina- 

 tion." Because of a number of difficult cases which have come to our 

 attention, we have discussed this subject with systematists in various 

 groups in botany and zoology, and the views obtained may be classified 

 as follows: 



(d) Some authors maintain that when a species of a genus has been 

 taken as the type of a new genus it is to be excluded from further 

 consideration in selecting the type of the original genus, subject, of 

 course, to the provisions mentioned under a and b (p. 59). All 

 systematists will doubtless agree that this position is sound. 



(&) Still other authors, however, go much further, and maintain that 

 when a species of a genus has been transferred to another genus, by 

 any author, rightly or wrongly, it is excluded from further considera- 

 tion in selecting the type of the original genus. Thus: 

 Oce-zia Zeder, 1800, with two original species: 



[ Cucullanus ascaroides} = Gcezia armata Rudolphi, 1801 ; and 

 inermis Zeder, 1800; transferred to Liorhynchus by Rudolphi, 1801 (but not as 

 type); returned to Cochins (namely, Gcezia renamed), by Zeder, 1803. 



