386 Dr. A. G. Butler — A Revision 



twelve, expressing his firm conviction that all the other 

 described forms were seasonal. So revolutionary a measure 

 naturally met with considerable opposition at first, and is 

 even now laughed to scorn by some lepidopterists ; but each 

 collection received from the tropical parts of the Old World 

 tends to ])rove that certain laws regulate the seasonal modifi- 

 cation of Pierine butterflies and are never departed from. 



In the wet season Pierina? are heavily marked with black 

 s| ots, borders, and sometimes veins, often on both surfaces 

 (though especially above) ; the under surface has a white or 

 yellow ground-tint. In the dry season the under (and some- 

 times the upper) surface shows much less black marking, and 

 is frequently suffused with clay-colour, ochreous, or rose-red ; 

 frequently, but especially when the ground-tint remains 

 white, the a])ical area of the primaries and the whole surface 

 ot the secondaries are irrorated or finely striated with brown. 



The seasonal character of the above differences has been 

 amply proved as regards the species of Tei-acolus, so that it 

 is now possible to recognize a dry- or a wet-season form at 

 sight ; nor is the fact that dated examples have been critically 

 examined by any means the only evidence upon which con- 

 clusions have been based, or even the unhesitating declarations 

 of collectors in India and Africa, for in some cases the one 

 form has been bred from eggs laid by the other, T. auxo 

 having been proved recently by Mr. Guy A. K. Marshall to 

 be the wet-season form of T. Iceiskamma^ as supposed by 

 Mr. Mansel Weale. 



Col. Charles Swinhoe objected to Capt. Watson's decisions 

 respecting the seasonal forms of certain Eastern Teracoli on 

 the ground that he took them all flying simultaneously at 

 Karachi — a fact which can be proved by an examination of 

 • the dates on the labels even of the Museum exauiples. It 

 must however, be borne in mind that in countries where 

 practically no wet season exists great variation is often to be 

 found as pointed out by me in the case of LimnaschrysijjpuSj 

 Catopsilia florella, &c. (Proc. Zool. Soc. 1884, pp. 478-503), 

 which there retain all the forms as simple sports of one variable 

 species which in other parts of the Old World become fixed 

 as local types. In like manner I find that phases answerable 

 to dry- intermediate, and wet-season forms exist in many 

 species of Karachi and Arabia, and are simultaneously pro- 

 duced. As an instance, Capt. Nurse bred T. Yerhurii and 

 T. evaqore from a series of exactly similar larva}, the perfect 

 insects emerging at the same season. 



Again, lest it should be supposed that the yellow or ochra- 

 ceous under- surface coloration was of specific importance, it 



