GENERAL FEATURES 19 



average size and appearance ; though frequently only one of the 

 sexes is represented ; those original examples then are "types," 

 and all the others which perhaps have been compared with them, 

 are "typicals." 



The loss by fire or otherwise of a "type" is a serious and an 

 irremediable misfortune, as it can never be replaced, and in such 

 a case doubt will always exist as to exactly what the type may or 

 may not have been, in color or markings. In case of types that 

 have been reproduced by color-photography the seriousness of the 

 matter of loss is greatly mitigated, as the colored plates will 

 always remain in existence, for comparison, and will not fade, or 

 become damaged by time or its inevitable vicissitudes. 



Many species have been described in inexcusably brief or am- 

 biguous language, seemingly with the intent not to tell it to any- 

 body, but this feature of practical entomology is, thank God, fast 

 disappearing. 



§8. The Species is the Folnhaiion. 



Students should bear in mind that the species is the foundation, 

 and that the genus and family names are more or less arbitrary, 

 the genera and the species contained in them being more or less 

 subject to change, as they become better known, and as wiser, or 

 less wise men set to work on them ; but the specific names, as 

 Rutulus, can never be changed, and you may be sure that that par- 

 ticular name Rutulus will always belong to that particular yellow, 

 swallow-tailed butterfly, whether some one sees fit to place the 

 name among the Lyccrnas or not. When looking up a butterfly 

 in the index, therefore, you should always look for the specific 

 name, rather than the genus or family name, because these latter 

 names are found in all sorts of queer places, according to the fancy 

 of the man who writes the list. 



§ 9. Sub-Species. 



Much difference of opinion may legitimately exist among men 

 as to the relative value of sub-species. In later years I have be- 

 come more of a believer in the value of small differences, if they 

 are constant, and to regard a small difference as positive and cer- 

 tain a thing as a wide one, and, of course, as of equal value; e. g., 

 Phyciodcs Pascocnsis. 



In varieties, where the differences grade insensibly into one 

 another, and into the species which is supposed to be the stem or 



