558 



NATURE 



[October 2, 1890 



India, &c. (such as E. harrisi, E. linncei, E. splendens, and 

 E. irawada) form a very characteristic group, while their general 

 type of appearance is imperfectly mimicked by a group of day- 

 flying moths {Amesia midama, A. alirts, A. sanguijlud). It is 

 extremely probable that the wonderfully close likeness of many 

 mimetic species arose by gradual stages from some general re- 

 ■semblance to a type of colour or pattern possessed by some 

 large group of unpalatable insects. 



The above-cited examples are some of them well-known, 

 they were chosen to illustrate the various different ways in which 

 mimicry occurs. 



Evidence for the evolution of mimetic resemblance has also been 

 forthcoming as the result of recent and hitherto unpublished work. 



Many moths have lost the scales which are characteristic of 

 the order of insects to which they belong, so that their wings 

 become transparent, and they mimic stinging insects such as 

 wasps or hornets. This is the case with two British hawk-moths 

 {Hemaris fuciformis and bombyliforviis). It is known that when 

 these moths emerge from the chrysalis, the transparent parts of 

 their wings are thinly covered with scales which are shaken off 

 during the first flight. The loss of the scales has now been 

 shown to be due to the rudimentary nature of the stalk at the 

 base of the scale and of the socket in which the stalk is in- 

 serted ; a closely-allied Indian moth {Hemaris hylas) was still 

 more completely denuded of scales, but in it also the rudiment- 

 ary sockets were found to be thinly scattered over the transparent 

 part of the wing. These facts suggested that all moths with 

 transparent wings may be found to repeat, in the course of their 

 own individual lives, the history of the change by which the 

 transparency has been attained by the species. Investigation 

 has supported this suggestion. The examination of two British 

 moths which resemble hornets or wasps was especially instruc- 

 tive. In one of these {Sesia apiformis) the mimicry is not so 

 perfect as in the other, and is therefore presumably of more 

 recent date ; in this moth the rudimentary scales which fall off 

 are comparatively perfect, while in the other species (.S". bem- 

 beciformis) they are far more degenerate, inasmuch as they have 

 been useless to the species for a far longer period of time. It is 

 interesting to note that these degenerate scales have not been 

 reduced in size in either species, but are, on the contrary, much 

 larger than the scales which are retained for the whole life of 

 the moth. In the allied " clearwings " of the genus Trochilium, 

 the transparency of the fore wing has been attained by the trans- 



parency of scales which are retained as well as by the loss of 

 scales. 



(2) Pseudepisematic Colours. This division not only includes 

 the examples of aggressive mimicry in which an animal resembles 

 another, and so is enabled to approach and injure it in some 

 way, but also the cases of alluring colouring in which an animal 

 possesses a lure which is attractive to its prey. 



Examples of the former are seen in the flies of the genus 

 Volucella, which are enabled to lay their eggs in the nests of 

 humble-bees, &c., because of their close resemblance to the 

 latter. The larvae of the fly feed upon those of the bee. 



Examples of alluring colouring. An Asiatic lizard {Phry- 

 nocephalus mystaceus) possesses pink flower-like structures at 

 the corners of its mouth, it is probable that flies, &c., are thus 

 allured. A terrapin {Macroclemmys Temminckii) from the 

 Southern States of America, when hungry, opens its mouth 

 and moves about two filaments at the anterior end of its tongue. 

 These look like worms moving in a crevice in the rocks, and 

 attract prey. The animal is otherwise perfectly motionless, and 

 resembles a weed-covered rock. The fish Lophius piscatorius 

 (the angler or fishing- frog) attracts its prey by a brightly coloured 

 lure placed over its large mouth, the rest of the body being con- 

 cealed. Certain deep-sea fishes allied to Lophius {Ceratias 

 bispinosus, C. uranoscopiis, &c.) have a phosphorescent lure 

 which attracts the other fish on which they feed. 



(3) Pseudallosematic Colours. A very striking instance was 

 discovered by Mr. W. L. Sclater in tropical South America. The 

 well-defended and abundant leaf-carrying ants {OEcodoma) are 

 mimicked by an immature Homopterous insect possessing a 

 shape and colour which closely resemble the ant together with 

 the piece of leaf it is carrying. 



IV. Epigamic colours are the bright tints and patterns dis- 

 played during courtship. As in other classes of colours the 

 same effects may be produced by the use of foreign objects 

 {Allepigamic). Examples are found in the various beautiful or 

 curious objects collected by bower-birds for the decoration of 

 their bowers. Especially interesting in this respect is the 

 Amblyornis inornata of New Guinea. 



Mutual relationship of the above-mentioned classes of colours. 

 It is clear that I. {Cryptic) and III. {Pseudosematic) colours are 

 closely related ; they may be conveniently grouped under one 

 head : — Apatetic or deceitful colours. The following scheme 

 will be found to represent the mutual relationships : — 



I. Apatetic Colours. 



(Resembling the environment, or some other species, 

 or acting as a lure.) 



A, Cryptic Colours. 



(Protective and Aggressive 

 Resemblances. ) 



B. Pseudosematic Colours. 



(False Warning and 

 Signalling Colours.) 



(i) Procryptic Colours. 

 (Protective Resemblances.) 



(2) Anticryptic Colours. 

 (Aggressive Resemblances. 



(i) Pseudaposematic Colours. 

 (Protective Mimicry.) 



(2) Pseudepisematic Colours. 



(Aggressive Mimicry and 

 Alluring Colouring.) 



II. Sematic Colours. 

 (Warning and Signalling. 



(l) Aposematic Colours. 

 (Warning Colours.) 



(2) Episematic Colours. 

 (Recognition Markings.) 



III. Epigamic Colours. 

 (Displayed in Courtship.) 



Allocryptic Colours. 



(Concealment gained by 

 use of foreign objects. ) 



Pseudallosematic Colours. 



(Resemblance to some 

 foreign object associated 

 with mimicked species.) 



Allosematic Colours. 



(Warning Colours of another 

 Animal made use of.) 



Allepigamic Colours. 



(Display of foreign objects 

 in Courtship.) 



IS-The comparatively new terms employed in the lecture were 

 due to the kind help of Mr. Arthur Sidgwick. The beautifully 

 painted lantern slides were due to the great skill and patience of 

 the artist, Mr. H. M. J. Underbill. The examples of Allo- 

 cryptic and many of those of Cryptic and of Allosematic colours 

 were painted from the living animals in the Marine Biological 

 Laboratory at Plymouth. Colonel Swinhoe had very kindly 



NO. 1092, VOL. 42] 



suggested good examples of mimicry among Indian butterflies, 

 and had lent from his beautiful collection the specimens for 

 copying. Mr. H. Grose- Smith had kindly lent the African 

 examples. Rev. F. J. Smith had most kindly helped in photo- 

 graphing the examples selected. Mr. W. R. MorfiU had kindly 

 translated Portchinski's Russian paper, thus rendering possible 

 the use of some very interesting examples. 



