March, i? 9 8 ] WEBSTER ! DEVELOPMENT OF DrASTERIA ERECHTEA. 29' 



size, each series comprising three individuals and measuring in length 

 as follows: i inch; lyL- inches; ii inches, and -flinch; i| inch; 

 and | inch. The larva measuring i ? V inch moulted on November 19th. 



On account of being almost continually absent from home, I was 

 now compelled to turn the larva? over to my assistant, Mr. C. W. Mally, 

 who gave them nearly all the attention they had throughout the re- 

 mainder of the time that they were under observation. 



After December 1, the larvae appeared to increase in size very rap- 

 idly, the larger ones becoming lighter in color, and could hardly be 

 distinguished from the yellowish and brown blades of grass, more or 

 less eaten, and along which they would stretch themselves and remain 

 for a long time, occasionally moving the head frcm side to side with a 

 sort of trembling motion. This protective coloration had been observed 

 from the time of the first moult of the larvae, the brown stripes and 

 greenish background blending with the discoloration of the part of the 

 blades of grass that had been attacked, while the lighter green corre- 

 sponded with the portions of uneaten epidermis, backed by the green 

 color of the blades behind them. As the larvae became more aged the 

 colors changed to a more decided brown hue, intermingled with yellow- 

 ish, and with this change there came a decided disposition to pass more 

 of the time nearer the base of the grass plants, where these colors pre- 

 dominated, than higher up, where the prevailing color was a uniform 

 green. Earlier in the life of the larvae, the upper portion of the blades 

 of grass were more generally attacked, none being cut off from below 

 and falling down to turn to yellow and brown, while now at this later 

 period, many blades Were eaten only for a short distance above the ground 

 and falling down took on the yellow and brown. Whatever might 

 have caused this change of habit, it was certainly not on account of the 

 lower portions of the blades being more tender and succulent, though 

 with the continually increasing bulk of the individual larva there would 

 naturally follow a greater aversion to activity, and a less disposition to 

 climb to the higher portion of the blades of grass. It seems to me that 

 we here have a most interesting case of adaptation, and one that was 

 not anticipated when these observations began. 



On December 3 the three larger larvae began to show signs of un- 

 easiness, crawling about the cages, and again stretched at full length on 

 the side of the same, and again down among the grass, feeding. 



December 7, one of the larger larva, which will be hereafter desig- 

 nated as No. 1, and the adult and chrysalis is shown under this number 

 in the illustrations, settled down in a corner of the breeding cage, fas- 



