574 MIMICRY 



of black feathers, and even the protuberance on the bill of the 

 Fhilemon being imitated by a similar enlargement of that of the 

 Mimeta. In the same way Mr. H. 0. Forbes in Timor Laut found 

 a corresponding species of Fhilemon and one of Mimeta so closely 

 alike that Mr. Sclater did not at first distinguish one from the other 

 (Froc. Zool. Soc. 1883, p. 199). In these cases it is pretty clear 

 that the Mimeta, which retains the dull coloration now characteristic 

 only of the immature among the Oriolidse,^ is rightly named the 

 mimic, since it is a comparatively weak bird, and must benefit by 

 being mistaken for the strong, pugnacious and noisy Fhilemon, two 

 or three of which will drive away Crows and even Hawks that 

 venture to perch on a tree they have occupied.^ 



On the information of Mr. Salvin, Mr. Wallace has cited 

 (Contrib. Nat. Select, p. 107) another very curious case of Mimicry in 

 Birds. This is furnished by Accipiter pileatus, a widely-ranging 

 species of Sparrow-Hawk Avhich near Rio Janeiro departs from 

 the plumage it wears in other places to assume that of Ear pay as 

 diodon (Hawk),^ a local species of insectivorous hajbit, with the 

 object, as suggested, of deluding small birds into the belief that it 

 is harmless in character. The similarity here extends to both 

 immature and adult plumages, which are very difierent. 



The most perfect case of resemblance between two Birds of 

 different groups seems to be one that, though announced a good 

 many years ago {Froc. Zool. Soc. 1870, p. 386), has been over- 

 looked by most writers on the subject. This is exhibited in the 

 genera Tylas and Xenopirostris, peculiar to Madagascar,'* the former 

 being indeed of doubtful alliance, but generally admitted to be 

 very near to Hypsipetes, which is placed either among the Turdidm 

 (Thrush) or Fycnonotidx ^ (Babbler), while Xenopirostris is one of 

 the Laniidse (Shrike), of which Family it wears the regular livery 

 — though apparently dimorphically, for examples of X. polleni may 

 be either white or bufi" beneath. But in either plumage this 

 species is counterfeited, feather for feather, by Tylas eduardi, so 

 exactly that but for a slight difference in size, and a marked dis- 

 tinction in the bill and feet — both of which are in Xeriopirosfris 



^ Mr. Wallace speaks of Mimeta "having lost the gay colouring " of Oriolus : 

 but I think the better way of stating the probability is as above. 



^ Mr. Wallace finding a peculiar MiTneta in Gilolo, hazarded the prediction 

 that a corresponding Friar-bird would be found there, which subsequently proved 

 to be correct [cf. Salvadori, Orn. Papuas. ii. p. 354). 



^ These species are rudely but recognizably figured, PI. col. 205 and 198. 



* Dr. Sharpe, it is true {Cat. B. Br. Mils. viii. p. 109), merges Mr. Elliot's genus 

 Clytoi-hynchus in Xenopirostris, making the range of the latter extend to N"ew 

 Caledonia. I venture to doubt the wisdom of this step. 



* By Dr. Sharpe {op. cit. \i. pp. 163-166) it is thrust into the bottomless pit, 

 -which he terms " Timeliidas." He recognizes 5 species of Tylas, M. Grandi- 

 -dier {Hist. Madag. Oiseaux, pp. 376-381) but one — with 3 local races. 



