'&!^ AND "^^^ 



JOURNAL OF VARIATION. 



Vol. IX. No. 9. September Ioth, 1897. 



The ova of Tephrosia bistortata (crepuscularia) and T. crepuscularia 



(blundularia) {lllmtrated Inj Plate). 

 By J. W. TUTT, F.E S. 



Hellins described the egg of T. crepuscularia (biwidularia) as fol- 

 lows :— " The egg is oblong, cylindrical and full, more conical' at one 

 end than the other ; the shell of dull appearance, without any gloss, 

 but also without any reticulation or granulation, except just in the 

 centre of the fuller end, where there is a small circular patch of oval 

 reticulation ; the colour of the egg is of a light bright green " 

 {E.M.M., vol. xiv., p. 236). 



We are indebted to Mr. Bacot and Dr. Riding for another move 

 in our knowledge of these tAvo species. The difficulty of comparing 

 the eggs side by side, owing to the fact that they emerge at different 

 seasons of the year, has been met by these gentlemen, by slightly 

 forcing pupae of T. crepiiscnlaria {bhuuhdaria) so as to obtain the 

 emergence of the imagines at the same time as the ordinary 

 emergence of 2\ bistortata. Not only has this been done, but 

 reciprocal pairings between the two species have been obtained, and 

 the eggs have proved fertile. Mr. Bacot was kind enough to send me 

 three lots of eggs. (1) T. bistortata eggs, the result of a pairing of 

 two typical insects of this species on Feb. 26th (PL vi., fig. B). (2) T. 

 bistortata eggs, fertilised by a male T. crepuscularia on Feb. 2(Sth (PI. vi., 

 fig. C). (8) T. crepuscularia eggs, the result of a pairing of two typical 

 specimens of this species on March 3rd (PI. vi., fig. A). These hatched, 

 respectively, on March 25th (27 days as ova), March 30th (30 days 

 as ova), April 1st (28 days as ova), but no stress can be laid on this 

 period, as the eggs were subjected to quite abnormal and varying 

 conditions of temperature. 



On March 10th, Mr. Baty mounted for me, side by side, several 

 eggs belonging to the first and third batches ; the eggs were then 12 

 and 7 days old respectively. The differences between the eggs, as 

 seen under a low power (only magnifying 70 diameters), are sufficient 

 to put at rest any possibility of their belonging to the same species. 

 The eggs belonging to the two sets were quite easily separable, both 

 by Mr. Baty and myself. 



Er/ej of T. bistortata (12 days old). — The egg of T. bistortata is, 

 to the naked eye, of a delicate pale pea-green colour. It is somewhat 

 cylindrical in shape, with rounded ends, and although the eggs are 

 slightly variable in size, and somewhat variable in shape, due to 

 certain indentations, evidently caused by external pressure at the 



