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d； freshly painted with the brightest vermilion； so as to colour the soles of its feet and parts of its stomach； a good idea of its appearance will be gained。〃 〃Instead of being nocturnal in its habits； as other toads are； and living in damp obscure recesses； it crawls during the heat of the day about the dry sand…hillocks and arid plains；。。。〃 The appearance and habits recall T。 Belt's well…known description of the conspicuous little Nicaraguan frog which he found to be distasteful to a duck。 （〃The Naturalist in Nicaragua〃 （2nd edition） London； 1888； page 321。）
The recognition of the Warning Colours of caterpillars is due in the first instance to Darwin； who； reflecting on Sexual Selection； was puzzled by the splendid colours of sexually immature organisms。 He applied to Wallace 〃who has an innate genius for solving difficulties。〃 （〃Descent of Man〃； page 325。 On this and the following page an excellent account of the discovery will be found； as well as in Wallace's 〃Natural Selection〃； London； 1875； pages 117…122。） Darwin's original letter exists （〃Life and Letters〃； III。 pages 93； 94。）； and in it we are told that he had taken the advice given by Bates： 〃You had better ask Wallace。〃 After some consideration Wallace replied that he believed the colours of conspicuous caterpillars and perfect insects were a warning of distastefulness and that such forms would be refused by birds。 Darwin's reply （〃Life and Letters〃； III。 pages 94； 95。） is extremely interesting both for its enthusiasm at the brilliancy of the hypothesis and its caution in acceptance without full confirmation：
〃Bates was quite right； you are the man to apply to in a difficulty。 I never heard anything more ingenious than your suggestion； and I hope you may be able to prove it true。 That is a splendid fact about the white moths （A single white moth which was rejected by young turkeys； while other moths were greedily devoured： 〃Natural Selection〃； 1875； page 78。）； it warms one's very blood to see a theory thus almost proved to be true。〃
Two years later the hypothesis was proved to hold for caterpillars of many kinds by J。 Jenner Weir and A。G。 Butler； whose observations have since been abundantly confirmed by many naturalists。 Darwin wrote to Weir； May 13； 1869： 〃Your verification of Wallace's suggestion seems to me to amount to quite a discovery。〃 （〃More Letters〃； II。 page 71 （footnote）。）
RECOGNITION OR EPISEMATIC CHARACTERS。
This principle does not appear to have been in any way foreseen by Darwin； although he draws special attention to several elements of pattern which would now be interpreted by many naturalists as epismes。 He believed that the markings in question interfered with the cryptic effect； and came to the conclusion that； even when common to both sexes； they 〃are the result of sexual selection primarily applied to the male。〃 （〃Descent of Man〃； page 544。） The most familiar of all recognition characters was carefully explained by him； although here too explained as an ornamental feature now equally transmitted to both sexes： 〃The hare on her form is a familiar instance of concealment through colour； yet this principle partly fails in a closely…allied species； the rabbit； for when running to its burrow； it is made conspicuous to the sportsman； and no doubt to all beasts of prey； by its upturned white tail。〃 （〃Descent of Man〃； page 542。）
The analogous episematic use of the bright colours of flowers to attract insects for effecting cross…fertilisation and of fruits to attract vertebrates for effecting dispersal is very clearly explained in the 〃Origin〃。 （Edition 1872； page 161。 For a good example of Darwin's caution in dealing with exceptions see the allusion to brightly coloured fruit in 〃More Letters〃； II。 page 348。）
It is not； at this point； necessary to treat sematic characters at any greater length。 They will form the subject of a large part of the following section； where the models of Batesian （Pseudaposematic） mimicry are considered as well as the Mullerian （Synaposematic） combinations of Warning Colours。
MIMICRY；BATESIAN OR PSEUDAPOSEMATIC； MULLERIAN OR SYNAPOSEMATIC。
The existence of superficial resemblances between animals of various degrees of affinity must have been observed for hundreds of years。 Among the early examples； the best known to me have been found in the manuscript note…books and collections of W。J。 Burchell； the great traveller in Africa （1810…15） and Brazil （1825…30）。 The most interesting of his records on this subject are brought together in the following paragraphs。
Conspicuous among well…defended insects are the dark steely or iridescent greenish blue fossorial wasps or sand…wasps； Sphex and the allied genera。 Many Longicorn beetles mimic these in colour； slender shape of body and limbs； rapid movements； and the readiness with which they take to flight。 On Dec。 21； 1812； Burchell captured one such beetle （Promeces viridis） at Kosi Fountain on the journey from the source of the Kuruman River to Klaarwater。 It is correctly placed among the Longicorns in his catalogue； but opposite to its number is the comment 〃Sphex！ totus purpureus。〃
In our own country the black…and…yellow colouring of many stinging insects； especially the ordinary wasps； affords perhaps the commonest model for mimicry。 It is reproduced with more or less accuracy on moths； flies and beetles。 Among the latter it is again a Longicorn which offers one of the best…known； although by no means one of the most perfect； examples。 The appearance of the well…known 〃wasp…beetle〃 （Clytus arietis） in the living state is sufficiently suggestive to prevent the great majority of people from touching it。 In Burchell's Brazilian collection there is a nearly allied species （Neoclytus curvatus） which appears to be somewhat less wasp… like than the British beetle。 The specimen bears the number 〃1188；〃 and the date March 27； 1827； when Burchell was collecting in the neighbourhood of San Paulo。 Turning to the corresponding number in the Brazilian note… book we find this record： 〃It runs rapidly like an ichneumon or wasp； of which it has the appearance。〃
The formidable； well…defended ants are as freely mimicked by other insects as the sand…wasps； ordinary wasps and bees。 Thus on February 17； 1901； Guy A。K。 Marshall captured； near Salisbury； Mashonaland； three similar species of ants （Hymenoptera） with a bug （Hemiptera） and a Locustid （Orthoptera）； the two latter mimicking the former。 All the insects； seven in number； were caught on a single plant； a small bushy vetch。 （〃Trans。 Ent。 Soc。 Lond。〃 1902； page 535； plate XIX。 figs。 53…59。）
This is an interesting recent example from South Africa； and large numbers of others might be addedthe observations of many naturalists in many lands； but nearly all of them known since that general awakening of interest in the subject which was inspired by the great hypotheses of H。W。 Bates and Fritz Muller。 We find； however； that Burchell had more than once recorded the mimetic resemblance to ants。 An extremely ant…like bug （the larva of a species of Alydus） in his Brazilian collection is labelled 〃1141；〃 with the date December 8； 1826； when Burchell was at the Rio das Pedras； Cubatao； near Santos。 In the note…book the record is as follows： 〃1141 Cimex。 I collected this for a Formica。〃
Some of the chief mimics of ants are the active little hunting spiders belonging to the family Attidae。 Examples have been brought forward during many recent years； especially by my friends Dr and Mrs Peckham； of Milwaukee； the great authorities on this group of Araneae。 Here too we find an observation of the mimetic resemblance recorded by Burchell； and one which adds in the most interesting manner to our knowledge of the subject。 A fragment； all that is now left； of an Attid spider； captured on June 30； 1828； at Goyaz； Brazil； bears the following note； in this case on the specimen and not in the note…book： 〃Black。。。runs and seems like an ant with large extended jaws。〃 My friend Mr R。I。 Pocock； to whom I have submitted the specimen； tells me that it is not one of the group of species hitherto regarded as ant…like； and he adds； 〃It is most interesting that Burchell should have noticed the resemblance to an ant in its movements。 This suggests that the perfect imitation in shape； as well as in movement； seen in many species was started in forms of an appropriate size and colour by the mimicry of movement alone。〃 Up to the present time Burchell is the only naturalist who has observed an example which still exhibits this ancestral stage in the evolution of mimetic likeness。
Following the teachings of his day； Burchell was driven to believe that it was part of the fixed and inexorable scheme of things that these strange superficial resemblances existed。 Thus； when he found other examples of Hemipterous mimics； including one （Luteva macrophthalma） with 〃exactly the manners of a Mantis；〃 he added the sentence； 〃In the genus Cimex （Linn。） are to be found the outward resemblances of insects of many other genera and orders〃 （February 15； 1829）。 Of another Brazilian bug； which is not to be found in his collection； and cannot therefore be precisely identified； he wrote： 〃Cimex。。。Nature seems to have i