188 Report on the Rules of 



30. 



The tenth edition of the ' Systema Naturae,' 1758, is the date of 

 the consistent general application in Zoology of the binary system 

 of nomenclature. This date therefore is accepted as the starting- 

 point of zoological nomenclature and of the operation of the Law 

 of Priority. 



31. 



The Law of Priority obtains, and consequently the oldest avail- 

 able name is retained, even : 



a. When any part of an animal is named before the animal 



itself, as, for example, in the case of fossils. 



b. When the larva is named before the adult. 



(Exception must be made, at least for the present, in the case of 

 the cestodes, trematodes, nematodes, acanthocephali, and acarines — 

 in a word, for animals which submit to a metamorphosis and change 

 of host ; otherwise many of these would have to submit to a nomen- 

 clatural revision, which would be only temporary in character and 

 lead to deep confusion, the final result and extent of which it is 

 now impossible to foresee.) 



c. When the two sexes of a species have been considered as 



distinct species or as belonging to distinct genera. 



d. When an animal presents a regular succession of dissimilar 



generations which have been considered as belonging to 

 different species, or even to different genera. 



32. 



When several genera or species have been proposed simul- 

 taneously, so that it is impossible to establish priority, preference is 

 to be decided as follows : — 



a. A generic name accompanied by specification of a type has 



precedence over a name without such specification. If 

 all or none of the genera have types indicated, that 

 generic name takes precedence the diagnosis of which is 

 most pertinent. 



b. A specific name accompanied by both description and figure 



shall stand in preference to one accompanied only by a 

 diagnosis or only by a figure. 



c. Other things being equal, the name is to be preferred which 



stands first in the book or article (Page-precedence *). 



d. But in all cases the name adopted by the first reviser of 



the group shall stand, even if such adoption is contrary 

 to these conditions. 



B — RECOMMENDATIONS. 

 33. 



When the word varietas is interposed between the specific and 

 * The expression "Page-priority" contains a contradiction.— C. W. S. 



