A discussion of ccrtaiu questions of nomenclature, as applied to parasites. 199 



in the interests of harmony to select D. crassicolle, for not only is it 

 the only illustratecl form (up to 1845) which comes into serious con- 

 sideration, but such a ruling would be in accordance with the views 

 of that not inconsiderable class of systematists who believe in page- 

 precedence, and also in accordance with the views of those who prefer, 

 if possible, to select the oldest species. 



Now let US inquire whether there was any reason for not select- 

 ing D. crassicolle as type — any reason developed by the writings of 

 later authors. 



9) The subgenus had been freely used, both directly and indirectly, 

 by various authors, but none of these writers had designated any 

 type species. 



10) Several of the species had been referred to or discussed by 

 various writers, but none had been eliminated as type of any new 

 genus. 



11) D. arrectiim had been placed in D. (Dicrocoelium) by Stos- 

 SICH, 1895, and so far as our records go, had not been returned to 

 Brachycoelium. Accordingly, there does not appear to be any reason 

 for selecting this species, over D. crassicolle. This view is rendered 

 even more justified by the fact that D. arrectum is problematic. 



12) D. retusum had been placed in D. {Bicrocoelium) by — ? — 

 and so far as our records go had not been returned to Brachycoelium. 

 Accordingly, it would not appear advisable to select this species over 

 D. crassicolle. This view is rendered even more justitied by the fact 

 that D. retusum is problematic. 



It would therefore appear that both D. arrectum and B. retusum 

 should be eliminated from competition with D. crassicolle. For prac- 

 tical reasons, also, to prevent confusion in selecting a misdetermined 

 species, "D. clavigerum Rud." of Dujardin, since it might easily 

 happen that some authors would Interpret D. clavigerum as type, the 

 third species of the list was eliminated. There remain now species 1 

 and 4, heteroporum and crassicolle. 



If heteroporum were selected, we should have gone quite contrary 

 to the view of three sets of nomenclaturists: those who believe in 

 page-precedence ; those who prefer to select the oldest species; those 

 who prefer to select a type which has a definite reference to an illus- 

 tration. If reasons were apparent for not following the views of 

 these men, in this particular case, I should not have hesitated an 

 instance in selecting D. heteroporum instead of D. crassicolle. No 



