118 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 9 



with its base against the base of the caudal fin. This remarkable color 

 character is the most easily seen characteristic of the genus and enables 

 specimens of Eurystole to be sorted without fail from their very similar 

 relatives. 



The genus as now defined contains a single species occurring from 

 Lower California and the Revillagigedo Islands south to Port Utria in 

 the Province of Choco, Colombia. 



The genus Eurystole is usually credited to Jordan and Evermann 

 (1896). As we have noted above, Jordan diagnosed the genus and desig- 

 nated its type species a full year earlier. Jordan does refer to Jordan and 

 Evermann as the authors of the genus ; but, since there is no internal evi- 

 dence to show that Evermann had anj^thing to do with the preparation 

 of the text on Eurystole eriarcha in Jordan's 1895 paper, the Interna- 

 tional Rules of Zoological Nomenclature require that Jordan be cited 

 as sole author. The senior author has discussed such cases of authorship 

 in Copeia, 1931, no. 3, p. 95. 



Note on the genotype. — It will be noted in the discussions below that 

 the supposed second specimen of Eurystole eriarcha, described and figured 

 by Jordan in 1895, is actually not a Eurystole at all, but a specimen of 

 what we call Nectarges nepenthe. Yet this same example is the one upon 

 which the current accounts of Eurystole eriarcha are based, and was the 

 only specimen in Jordan's hands when he founded the genus Eurystole. 

 There is, therefore, some doubt as to whether the generic name Eurystole 

 should be held to apply to the genus typified by the species eriarcha or to 

 the genus we here call Nectarges. 



This is one of those numerous instances in which a generic name was 

 based upon a misidentified type species. Opinion 65 of the International 

 Commission on Zoological Nomenclature discusses such cases. The Com- 

 mission says, "If an author designates a certain species as genotype, it is 

 to be assumed that his determination of the species is correct; if a case 

 presents itself in which it appears that an author has based his genus upon 

 certain definite specimens, rather than upon a species, it would be well to 

 submit the case, with full details, to the Commission. At the present 

 moment it is difficult to lay down a general rule." It is evident that the 

 Commission has never definitely decided upon this question, which is not 

 covered by the International Rules. 



In the present instance it is clear that Jordan's 1895 description of 

 Eurystole was based upon Stanford 2689, an example which is generically 

 different from the type of Eurystole eriarcha, but it is equally clear that 



