SCIENTIFIC NOTES. 



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SCIENTIFIC NOTES AND OBSERVATIONS. 



Pupal dimorphism of Leioptilus tephradactyla. — The pupal 

 dimorphism of this and other Plumes is, or is supposed to be, well 

 known, but I don't know that any observations have been put on 

 record in this species showing that the dimorphism is exactly parallel 

 with that of Pieris rrtj»;rtc and other butterflies of which many observers- 

 have written. On June 10th, 1911, I examined a pot of Solidaffo 

 virfiaurea on which 1 had a number of larvae of L. tephradactyla, which 

 I expected to find pupated. I found several score pupae, of which 

 40 or 50 were on leaves of the plant, and these were without exception 

 of a green colour. About a score were on dead or dying leaves of a 

 brownish colour under the plant ; some of these pupte were green, and 

 some grey, but the latter with usually some greenish tone. On the 

 zinc cage were eleven pupa5 ; these were, without exception, grey, and 

 none had any greenish tmt. Both forms had the black markings 

 characteristic of the pupa ; these were weak, or practically wanting on 

 most of the green ones ; but very pronounced on the grey ones. The 

 essential difference between the two forms is in the green or grey- 

 ground colour, but a quite strong secondary difference is in the 

 strength of the dark markings, making the grey form much darker 

 than is caused by the actual ground colour. Mentioning these 

 circumstances to Mr. Tonge, he told me that he had two pupae of the 

 species fixed side by side, and that one was green and one grey, an 

 occurrence which seemed subversive of any generalisation from my 

 observations. These pupae were produced, and assuredly one was 

 green and one grey, and they were almost, if not quite, side by side. 

 They were on the lid of a glass-topped round tin box; one under the 

 rim was grey, the other beside it was on the glass, and no doubt took 

 its colour stimulus from the leaves below it in the tin, the glass would 

 have no effect, and the tin rim to the glass was of course a mere line 

 from its position. This apparent exception, then, seemed fully to 

 prove the rule, and shows the caution necessary in accepting reports 

 of a casual observation, even by a good observer. These pupae emerge 

 after a very short time, so there is no question here of a dark form 

 being related to hibernation. As in the case of P. rapae and others, 

 the determining stimulus acts during the short period between selection 

 of a pupal position and the actual moult to pupa. — Dr. T. A. Chapman, 

 Betula, Reigate. 



Migratory (?) flights of Libellula depressa. — On Saturday, 

 June 3rd, I saw one of the most wonderful sights it has ever been my 

 lot to witness, viz., a flight of dragonflies passing down the coast, all 

 flying the same way, and never swerving out of their course, except 

 when anyone attempted to strike at them ; then they dodged (and they 

 could dodge) and mounted into the air until nearly out of sight. 

 Singly, and in twos or threes, every second or so, never an interval of 

 a minute, did they pass, and as this was spread over a breadth of 

 coast, say, 300 yards wide, you can imagine the numbers that must 

 have passed during the morning. I first noticed them about 9.15 a.m., 

 and went home to lunch about 12.30 p.m., when they were still passing 

 on at the same rate. I had no net with me, but managed to obtain 

 one of them, which Mr. Turner has identified as Lihellitla depressa. 

 I returned in the afternoon, but the flight had ceased then, and I saw 



