GENERIC NAMES OF BUTTERFLIES 373 



the dates of publication of the plates in Hiibner's Samml. exot. Schmett. in the light of the 

 discovery of Hiibner's manuscripts, was very similar to that already described in the note on 

 the name Pontia Fabricius. In this case also a well-known Fabrician name — Morpho 

 Fabricius, 1807 — was found to be a subjective synonym of a Hiibnerian name — the name 

 Potamis Hiibner, [1807] here under consideration — and, as these names were both pub- 

 lished in the same year there was a risk that through the discovery of additional information 

 as to the exact dates on which these names were published, the name Potamis Hiibner might 

 be found to have priority over, and would therefore replace, the name Morpho Fabricius. 

 The greatest confusion would inevitably have ensued, since the name Morpho is the eponym 

 of the family Morphidae, whereas the name Potamis was totally unknown in connection with 

 this family. 



It was accordingly decided to submit this case, concurrently with that of the names Pontia 

 Fabricius and Mancipium Hiibner to the Commission with a request that in this case also the 

 Fabrician name be protected under the Plenary Powers against the Hiibnerian name (Potamis). 

 This case, which was placed before the Commission in 1935, was dealt with by the Com- 

 mission with the other names referred to above in its Opinion 137, promulgated in 1942. 

 The ruling then given by the Commission under its Plenary Powers was that the name 

 Morpho Fabricius was to be accorded precedence over its subjective synonym Potamis 

 Hiibner ; this decision, like those relating to the other names in question, was amplified by 

 the Commission in 1954 m its Direction 4, in which it ruled that the Hiibnerian names rejected 

 under the Plenary Powers in Opinion 137 were to be treated as having been suppressed under 

 the foregoing Powers in that Opinion for the purposes of the Law of Priority but not for 

 those of the Law of Homonymy. The name Potamis Hiibner (as of the Samml. exot. Schmett.) 

 was thereupon placed on the Official Index of Rejected and Invalid Generic Names in Zoology 

 as Name No. 212. 



POTANTHUS Scudder, 1872, 4th Ann. Rep. Peabody Acad. Sci. 1871 : 75. Type-species 

 by original designation : Hesperia omaha Edwards, 1863, Proc. ent. Soc. Philad. 2 : 21. 



For many years it was impossible to assign a systematic position to the genus Potanthus, 

 because it was impossible to determine the identity of the taxon represented by its type- 

 species, the nominal species Hesperia omaha Edwards. Both that species and also the only 

 other species (Potanthus californica Scudder, then a newly established species) were stated 

 by their original authors to have been taken in the United States : Edwards giving Colorado 

 as the locality for Hesperia omaha ; Scudder giving California as the locality for Potanthus 

 californica. No known United States species correspond with the descriptions given by 

 Edwards and Scudder for the nominal species cited above respectively and named by those 

 authors. This led to consideration being given to the possibility that the original localities 

 cited for these species were incorrect and that in fact the type-material might have been 

 obtained from somewhere outside the United States. After a discussion of this matter 

 between the late W. H. Evans and myself it was arranged that the assistance of the British 

 Museum should be sought to obtain the loan of the types or surviving paratypes of these 

 nominal species (and also those of the equally mysterious and unrecognizable Hesperia mingo 

 Edwards, 1866) from the various institutions in the United States in which they were pre- 

 served. The very generous response to this request made it possible to solve these long- 

 outstanding mysteries. Full particulars of the Institutions which assisted in this way are 

 given in the paper published in 1935 (Stylops 4 : 1 00-101) in which Evans made known the 

 conclusions which he had reached in the light of the material so made available. Of the three 

 nominal species investigated only Hesperia omaha Edwards is relevant in this present question. 

 Of this nominal species through the kindness of Captain Roswell C. Williams a paratype and 

 a watercolour painting of the holotype were made available for study. The paratype was 

 found to be a female of the species to which in 1879 (Ann. Mag. nat. Hist. (5) 15 : 191) 

 Butler had given the name Pamphila maesoides, of which the male holotype from Malacca 

 is now in the British Museum. Referring to the watercolour of the holotype of Hesperia 

 omaha, Evans added that it too belonged to Pamphila maesoides Butler. 



