402 



KNOWLEDGE & SCIENTIFIC NEWS. 



[Al'RIL, 1906. 



The ColorsLtion of 

 MaLmimacls OLiid Birds. 



By J. Lewis Honhote, M.A., F.L.S., F.Z.S., M.B.O.U., &c. 



(('i)ntinin'd from page 373.) 



So far, our remarks have been restricted to those 

 " poecilomeres " which were first to be noticed as 

 " centres of bleaching " in Ratufa, but a closer ex- 

 amination will show that, in addition to those already 

 mpiitloncd, sevcr.-il other spots are to be noted. 



Although in the present state of our knowledge we 

 cannot show these to be actually " bleaching centres " 

 in any particular species, yet they correspond so closely 

 ivith those " poecilomeres " already mentioned that 

 there can be no doubt that they arise in q similar 

 manner. 



The complete list of " poecilomeres " is, therefore, 

 as follows : — 



On the head, we have the nose, lips, chin, crown, 

 occiput, ears, and the eye. This last has, in reality, 

 two spots, the one in front of and above the eye (supra- 

 orbital), and the other below and behind it (post- 

 orbital). 'J'lu- wliile-earcd cob {('obns maria) gives us 

 a good example of the eye spots. 



On the upper pari of ihc body we have the shoulders, 

 thighs, rump, tip of the tail, wrists, and ankles. 



The under parts are, as a rule, more uniform in colour, 

 but where any tendency to diversity is shown we find it 

 taking place along fixed lines, and the following spots 

 may be noted as " poecilomeres, viz., the chin, inside 

 of the arms and legs, fore-end of the sternum, and the 

 vent or pubic regions. The best example of underside 

 " poecilomeres " is to be found in a squirrel of South 

 America (S. dorsalis), which is, as a rule, ochreous 

 underneath, but shows in many individuals permanent 

 white patches on most of the spots. In 5. prveri, a 

 Chinese squirrel, the armpits and inside of the thighs 

 and vent are rufous, while the rest of the underparts 

 of the body are white. 



.'\mong birds the white ring of the ring ousel, the 

 white breast of the female frig;ite bird, the red breast 

 of the shell-duck, the violet patch of the jambu fruit 

 pigeon, and the red patch of the blood-breasted pigeon, 

 are good examples of the sternal " poecilomerc. " The 

 red vent of the woodpecker and white \cnt of the 

 moorhen are examples of another patch. 



As regards the face markings among birtis, the 

 common kingfisher affords a good example, showing us 

 the white chin patch, the green malar stripe, corre- 

 sponding to the lower lip in mammals, the dark mandi- 

 bular stripe, the rufous supraorbital and postorbital, 

 and white oral patch. To continue multiplying in- 

 stances of the.se spots is unnecessary. Anyone inter- 

 ested in the subject has only to go through any collec- 

 tion of birds or mammals to find instances on all sides. 



It has been further pointed out to me, and is, per- 

 haps, not without its significance, that the spots in 

 which hair is found in man are all to be found among 

 these "poecilomeres." 



Unfortunately I am not a physiologist, nor have I 

 been able to find in any book' facts which would tend 



* lam not unmindful of Captain Barrett-Hamilton's paper (already 

 referred to) where he is inchned to consider the white patches to be 

 due either to the presence of subcutaneous fat or to the direct 

 contact of bone with skin, but for the present I prefer to express 

 no definite opinion on this point. Mr. Tylor lias also some 

 suggestive ideas on lliis point. 



to throw light on the nutrition or otherwise of these 

 particular spots, but there is little doubt that any 

 practical physiologist, who could afford the time, 

 might, by investigations carried on in this direction, 

 add a considerable amount tO' our knowledge of the 

 cause of the patterns and markings in animals. 



Most of the warning and protective markings will be 

 found situated on these " poecilomeres," but there is 

 one point which I would wish to impress, namely, 

 that these same markings will be found in hundreds 

 of cases, where, unless they were looked for, they would 

 pass imno'liccd, being merely represented by differences 

 in shade so' slight that they cannot possibly be said to 

 serve any piuposes of protection, warning, or recogni- 

 tion, but, in my opinion, form additional evidence to 

 show that the brighter and more conspicuous markings 

 have a much deeper significanre than th;it put forward 

 by those who^ believe the theory of n.itural sclrrtion to 

 be all sufficient. 



As examples of this, I will notice two or three from 

 among our local British birds. In the hen hou.sc 

 sparrow, for instance, the rump is unspotted; the rump 

 of the hen chaffinch is slightly greener than the rest of 

 the back; the hen yellow-hammer shows the dark car 

 patch and light malar stripe and chin. The linnet 

 shows the two eye patches. The young cuckoo will 

 often show a few white feathers on the occiput or 

 crown. The wryneck (Jtinx torquilld) shows f.aintly 

 the beginnings of the chin or malar stripe in having 

 the feathers of those parts, although resembling the 

 rest in pattern, white instead of yellow, while the dark 

 patch in front of the barn owl's eye and the yellowish 

 tinge on the breast are further evidence that the small- 

 est of these markings is no mere sport or accident, but 

 the result of deep-seated physiological causes. Among 

 our British mammals the white spot on the forehead 

 sometimes found in the common hare may also be ac- 

 counted for on the s.ame lines of reasoning. 



" Poecilomeres " also manifest themselves in some 

 species in a transitory state. The stoat offers a good 

 example, for when it commences to assume its white 

 winter dress it does so along well-defined lines. The 

 first spots to show white are the thighs, whence the 

 white spreads down the hind limbs and along the sides, 

 gradually encroaching more and more on the colour of 

 the back. It then appears on the rump and shoulders, 

 spreading down the tail from the former, and down the 

 forelimbs and over the shoulders from the latter. The 

 head remains coloured to the last, but when it begins 

 to change, the lips, no.se, and ears are the first to 

 whiten, the white from the nose extending up between 

 the eyes as far as the forehead, thus leaving the eyes, 

 postorbital patch, and frontal patch the last to turn. 

 In a lesser degree this may be observed in many 

 mammals ; the common hare, for instance, showing a 

 tendency to lighten on the thighs on the approach of 

 winter. 



Among birds the following example has come under 

 my notice recently, and, with further observation, 

 doubtless instances might he indefinitely multi- 

 plied. During the past winter I have had under ob- 

 servation two young shovellers [Spatula clypcata) that, 

 during the early months of the year, have been slowly 

 assuming the metallic-coloured head of the adult. 

 Both birds performed this process in the same manner. 

 The first sign of the metallic plumage was observed on 

 the postorbital and ear patclies simultaneously; these 

 two patches spread and joined together forming a 

 metallic patch similar in range and definition to that 

 found permanently in the m.alc teal. The patch of 



