MEANING OF SHAPRS AND COLOURS OF THE MEMBRACID.E. 9 



T can imagine no more interesting study for the tropical American naturalist than 

 the attempt to discover the meaning of these remarkable shapes by careful observation 

 of the living insects under as many different conditions as possible, and especiall}' 

 during the periods of prolonged rest and entire quiescence. It is during these latter 

 times rather than in periods of activity (including the frequently repeated brief 

 intervening pauses) tliat the true meaning of a cryptic appearance and instinct is to 

 be sought. Thus insects which are about by day should be watched going to rest, 

 and then observed from time to time during the hours of darkness; conversely, 

 nocturnal forms should be tracked and then watched by day. Insects which require 

 the hottest sunshine should be studied in exceptionally cold cloudy weather, &c. 

 In thus looking out for the times of com^jlete repose, when a cryptic appearance 

 is of the highest importance, Mr. Nelson Annandale's observations in Malacca 

 (1899-1900) should be remembered. He informs me that insect-eating animals retire 

 to rest during the hottest hours of the day, and that at this very time insects, 

 including such cryptic forms as the stick-like Phasmids, move about freely, assume 

 positions and occupy envii'onments in which they are quite conspicuous. Any 

 observer who neglects to take account of this aspect of the question can only commit 

 himself to random criticism like that which has been often urged against the inter- 

 pretation of the wonderfully cryptic underside of butterflies of the genus Kallnud. 

 Because these insects have been seen in conspicuous positions and attitudes during 

 the short pauses between successive flights it has been argued that the dead-leaf- 

 like underside cannot be for concealment. Let any such observer watch a KalUma 

 to rest at the close of a day's active flight, and his notes and criticism on the subject 

 will have value. As it is we are only confronted by the aimless objection that an 

 adaptation developed for one purpose is not made use of for another, and with tliis 

 conclusion the movements and attitudes of our English Vanessidce, with their cryptic 

 undersides, had long ago familiarised us. 



We now reach the second sub-family of Mr. Buckton's classiflcation, the IIopJoplw- 

 r'lnce. The cryptic resemblance to thorns in the genus Umhouia (Plates XVI. and XVII.) 

 is well known, but here, too, exact observation of the living insects is much wanted. 

 The manner in which the red stripes are developed on the green or greenish thorn- 

 like pronotum is very realistic and convincing. The fact that the females are far 

 more completely thorn-like than the males (compare Figs. 1, 2, 3 with 4 and 5 on 

 Plate XVI.) may be nierel}^ another example of the general principle that the latter sex, 

 when it differs from the former, is more cryptic or more completely mimetii^ as the 

 case may be. The greater needs of one sex have been met by increased perfection in 

 those adaptations which are the chief means of defence. 



The remaining genera of the HojjJojjIioriiice, figured by Mr. Buckton, viz., Triqiiclra, 



