46 [February, 



fusca ; while Pericoma palustris, mutua, and the nameless species from the 

 Sehwarzwald, together with P. cognata, which was not exhibited, have the tentacular 

 type of mcsopleural appendage seen in P. auriculata. Mr. H. St. J. Donisthorpe 

 read a paper, entitled, " The Life History of Clythra ^-punctata ;" and Mr. G-. 

 W. Kirkaldy communicated " A Memoir upon the Rliynchotal Family Capsidce." — 

 II. Rowxand-Bkown, Hon. Sec. 



ON TIIE SPECIFIC VALUE OF BYBLIA GOTZIUS, Heebst. 

 BT GUY A.. K. MARSHALL, F.Z.S. 



Some years ago I recorded the statement of Mr. J. M. Hutchin- 

 son, of Esteourt, Natal, that he had bred a specimen of the wet season 

 form of Byblia ilithyia, v. acheloia, Wallg., from an egg laid by typical 

 ilithyia, Drury (A. and M. Nat. Hist. (G), xviii, p. 338, 1896), as a 

 result of which 1 followed Mr. Trimen in regarding i?. Gotzius, Hbst., 

 and its local race acheloia, as merely varieties of Drury's insect. This 

 view was afterwards opposed by Dr. Dixey in his interesting review 

 of the genus (Proe. Zool. Soc, 1898, p. 376) ; and later also by Prof. 

 Chr. Aurivillius (lihop. Aeth., pp. 158, 159). 



During the past season I determined to obtain further evidence 

 on the point by breeding these insects from the egg; Salisbury being 

 a specially suitable locality for such an experiment, owing to the fact 

 that both forms occur here in about equal numbers, which 1 do not 

 remember to have observed in any other part of South Africa. My 

 attempts to induce the $ s to lay in captivity were futile, but with 

 the expenditure of a considerable amount of time, I succeeded in 

 obtaining from twelve to fifteen authenticated eggs of each form in 

 the field. The food-plant and the general habits of the two insects 

 appear to be identical, and they both possess the curious habit, which 

 occurs among a good many of our butterflies, of laying most of their 

 eggs indiscriminately at some little distance from the food plant : an 

 instinct probably developed to evade the attacks of various egg- 

 destroyers, which would principally frequent the food-plants of their 

 victims. From these eggs I obtained fourteen butterflies in all, and 

 in every case these bred true to their respective parents. This evi- 

 dence would not be very cogent in itself, were it not supported by 

 certain differences exhibited by the two forms in their larval and 

 pupal instars. 



In the case of the larvae it seemed at first as though there might 

 be a reliable distinction in the structure of the spines, but with the 

 examination of further material it became evident that there was a 

 certain amount of individual variation in this direction which rendered 

 the character useless. 



