Ornithological Nomenclature. 433 



rufa by Bechstein for a bird which that excellent field-natu- 

 ralist describes so accurately that no one can doubt for a 

 moment that he is describing the Chiffchaff. I therefore 

 propose the following rider to Rule 12 : 



" Names accompanied by descriptions so imperfect as 

 to be incapable of identification with any known species, 

 must be consigned to the oblivion of prelinnsean names, 

 so that their existence shall be no bar to the adoption 

 of the same name when given by a later writer." 

 This rule will also apply to and provide for the following 

 case : 



Acrocephalus aquaticus, Newton's ed. Yarr. Brit. B. i. p. 

 380; Dresser, Birds of Eur. pt. li. 



The Aquatic Warbler has by no means a clear title to its 

 name. Scopoli's bird may have been either a Sedge-Warbler 

 or an Aquatic Warbler ; but his description is inconsistent 

 with either of them. Neither Gmelin nor Latham appear 

 to have known the bird, but to have simply copied Scopoli. 

 Bechstein, Meyer and Wolf, and Naumann were well ac- 

 quainted with the species, but identified it, probably incor- 

 rectly, with the Motacilla salicaria of Linnaeus, a name which 

 has been transferred from one species to another until it has 

 long ago ceased to have any definite meaning or any scien- 

 tific value. Temminck was the first writer to use the name 

 aquatica for a clearly defined species ; and since his name has 

 been in general use, and has not been extensively, if at all, 

 applied to any other species, we are, in my opinion, justified 

 in calling the Aquatic Warbler Acrocephalus aquaticus 

 (Temm.), consigning the Motacilla aquatica of Gmelin and 

 the Sylvia aquatica of Latham to the Lethe of prelinnaean 

 oblivion. 



Turdus dubiuSj Dresser, Birds of Eur. pt. Iviii. 



The Thrush hitherto known as Turdus fuscatus of Pallas is 

 christened Turdus dubius by Dresser, because that writer has 

 "satisfied himself" that Bechstein's description of a Thrush 

 which was sent to him from Coburg refers to an immature ex- 

 ample of Pallas's bird. After carefully reading over the de- 



