298 THE entomologist's record. 



ages of the Rook, with Special Reference to the Moult of the Face." 

 The adult rook's " face " is bare, whereas the carrion crow's " face " is 

 covered with bristle-like feathers, and it has long been a disputed point 

 as to whether the former gets its bare face by means of a moult, or by 

 abrasion of the feathers when digging the ground for food. Mr. 

 Witherby has been cari-ying out investigations on birds shot in a wild 

 state, in every month and nearly every week of the year for two years, 

 and proves pretty conclusively that the feathers are lost in the first 

 winter-moult, after January, and not by abrasion. He summarises 

 the experiments that have been carried out from time to time on birds 

 in captivity, and in one instance, "even after its second winter-moult, 

 the face was fully feathered, and in another case a bird did not get a 

 bare face until its second autumn-moult." He remarks, " It is well 

 known that birds in captivity often moult most irregularly, and this ?V 

 a (fooil viatance of the dani/er of drawintj conclusions regarding iiioidt and 

 sequences of jduinoije from captive birds." My contention is that a 

 similar danrjer exists from drawing conclnsions regarding the rejecting of 

 insect food bi/ captive birds. 



Mr. Curtis is mistaken on p. 156, when he assumes that I " view 

 the question of protective coloration from the narrow standpoint of 

 attacks on lepidopterous imagines only," as I think I have sufficiently 

 indicated in the above notes. True, I only mentioned Polia eld in my 

 original note, but then I was replying to a previous note on this insect. 

 I would suggest to Mr. Curtis that he should take into consideration, 

 not only the attacks by birds, but also the attacks of spiders, bats, 

 lizards, ichneumon and other Hies. 



Mr. Curtis says on page 157, " Tlie theories iroiild lose their value to 

 me entirely if theg could not be apjilied throughout and to their logical 

 extremitg.'" Yet at the end of the next paragraph he finds it necessary 

 to cover himself by saying, " the supposed exceptions are the result of 

 interaction of laws which ve hare failed to elucidate." In the same para- 

 graph he says, " / do not believe that natural laws operate in a piece-meal 

 style, everything tliut I know tends to make me believe that every law in 

 nature is carried into operation in its entirely," with which I agree. 



The Mimicry theory falls far short of this, however, otherwise all 

 the "palatable" species would receive protection in the same way,, 

 and I fail to see why some "palatable" species should be protected 

 at the expense of others. Again, how is it that " distasteful or 

 unpalatable" species do not become pests through their immunity 

 from attack, what keeps their numbers down ? The fact is " nature " 

 is one vast tragedy, and the lucky ones escape. The birds feed on 

 insects, mollusca, worms, etc. ; ichneumon fly larvse on lepidopterous 

 larvae; stoats, adders, crows, etc., feed on young birds and so on. If 

 these natural laws work for the protection of butterflies, why do they 

 not also operate for the protection of young birds, whose mortality is 

 so high, bj' making them distasteful? I think the answer is obvious. 

 By doing so " nature " would upset the balance and we should be 

 overrun with birds, and so it would be with the supposed " unpalatable" 

 butterflies and moths. With regard to the striking resemblances 

 between different species of butterflies, etc., this may be a reversion to 

 type of marking, of a common ancestor. The fact that they are 

 distinct species now is an exemplification of the variability of 

 "physical means and machinery" producing similar results, as regards 



