MEANING OF SHAPES AND COLOUBS OF THE MEMBRACID^. 13 



rest of the world in the amount and variety of mimetic resemblance in insects we see 

 the outcome of a selective environment which may well have developed cryptic forms 

 more strange and complex than any that are known elsewhere. But the possibility 

 of mimetic likeness in Ci/jjlioiiia and Boci/diirm should not be left out of account in 

 tlie attempt to solve the problem. The fact that no undoubted explanation is forth- 

 coming is by no means surprising ; and even when tlie living insects are studied 

 under natural conditions it is quite likely that a solution may be long delayed. Every 

 English entomologist has known from boyhood the " Comma " or " C " on the under- 

 side of the wings of the butterfly Grapta C-album ; yet tlie explanation of a cryptic 

 resemblance to the light seen through a semicircular crack in a weather-beaten 

 fragment of dead leaf, although sufficiently obvious when once stated, was only given 

 a few weeks ago {Proc. Eni. 8oc. Loud, for May 6, 1903). The writer hopes that 

 Mr. Bucktou's figures of species of these two genera may induce naturalists in South 

 America to make a special effort to solve this deeply interesting problem. The 

 observer should keep a very open mind and not neglect effects produced by com- 

 munities of individuals of the same species, nor the possibility that a single Membracid 

 surmounted by the branching appendages of its pronotum may resemble a combination 

 of two quite different forms, such as an ant or spider attacking or carrying its 

 insect prey. Figs. 4, 5, G, and 7 on Plate XXXIIL, and la on Plate XXXIV., should 

 be looked at from this point of view. 



Passing to other genera, Pojjjjea (Plate XXXIV.) presents structures similar to 

 Cyphonia, but on a somewhat smaller scale. In Ctrei^a, Sfidocephala, Cenirogonia, 

 Phacifsa, Eurytea, Aciifalis, Micritfahs, Trachy talis, and Folyylypia (Plates XXXV.- 

 XXXVIII.) we meet with shapes and colours, which generally appear to be exjjlicable 

 without difficulty as examples of protective (cryptic) resemblance to common plant 

 structures. Species of the last-named genus (Plate XXXVIII.) appear to resemble 

 elongated fruits or seeds, although the idea of mimicry of a Brenthid beetle should 

 be tested by observation before being dismissed. Entylia, Publilia, Metheisa, and 

 Oxyyoiiia (Plates XXXIX. and XL.) are probably to be explained in the same way, 

 in some cases resembling roughened bark or irregular fruits or seeds, in others 

 perhajjs buds. 



Parai/lojiai' diptcroides (W. W. Fowler), tigured by Canon Fowler on Plate VII., 

 Figs. 10 and lOa, of his monograph in the Biologia, is apparently a beautiful mimic, 

 and the aculeate Hymenoptera of its sub-region (Central America) should be 

 examined for possible models. Figured with wings outspread the superficial 

 resemblance to a fly is undoubtedly strong, but the effect upon the contour of the 

 dark coloured basal half of the depressed tegmina must be taken into account. 

 Canon Fowler in stating (p. 102) that the species "has the ajjpearance of a larye 



