35 



tion ; it, therefore, appears that, like its northern repre- 

 sentative, the true Anosia plexippus, the southern form had 

 the migratory habit similarly developed. 



Mr. Hawes exhibited Pieris napi, L., and read the 

 following notes : " The series of P. napi exhibited were bred 

 from ova laid by the parent insect, which was taken near 

 Bentley, Suffolk, on or about June loth of last year (i8gi). 

 The larvae were fed on the leaves and young stalks of 

 Alliaria officinalis, on which plant I have found the full- 

 grown larvae on two occasions in the north of London. 

 They fed up rapidly and well, only a small percentage of 

 deaths occurring, and by about July 5th had begun to assume 

 the pupa state. On July 21st the first imago put in an ap- 

 pearance, followed at short intervals by twenty more, to 

 July 31st, i.e., seven males and fourteen females. After 

 July 31st there was a complete cessation in emergence. I 

 have a note, written at the time, to the effect that ' a cool 

 day retards emergence,' not thinking that the whole of 

 August, although below the average temperature, and 

 September, with at least one brilliant week, would be power- 

 less to entice the butterfly from its chrysalis. It should be 

 mentioned that the insect was kept through all its stages in 

 a room at the top of the house, which, with a southern aspect, 

 is exposed to all the heat and cold without artificial pro- 

 tection. The larvae were brought up in large gallipots, and 

 so kept cool and feeding steadily. When the last moult had 

 been got through, they were all transferred to an ordinary 

 wooden cage, and there pupated. This cage was not re- 

 moved from the room until the middle of October, when, 

 with others, it was placed under the seat of our summer- 

 house, exposed to the north. Being brought in about April 

 20th, and placed on a window sill in the sun, between May 

 6th and 20th, thirty-one more imagines appeared, about one 

 third males and two-thirds females. I should like to call 

 attention to a certain amount of variation in the veining on 

 the underside. In the summer form the males are more 

 prominently marked than the females ; in one specimen there 

 is as much pencilling as in an example of the spring form, 

 but the spring form is generally well defined, as usual. In 

 the females the tendency is to slight pencilling, and in both 

 summer and spring forms to an abrupt shortening of the 

 pencilling. In conclusion, I can only suggest, what is 

 perhaps apparent enough, that the cool summer of last year, 

 together with the fact that the nights under a partly open 

 window in a top room, in a locality which is 350 feet above 



