106 MIMICRY, AND OTHER PEOTECT1VE 



imitated by the Mimeta. In the island of Morty 

 (north of Gilolo) there exists the Tropidorhynchus 

 fuscicapillus, of a dark sooty brown colour, especially 

 on the head, while the under parts are rather lighter, 

 and the characteristic ruff of the nape is wanting. 

 Now it is curious that in the adjacent island of Gilolo 

 should be found the Mimeta phacochromus, the upper 

 surface of which is of exactly the same dark sooty 

 tint as the Tropidorhynchus, and is the only known 

 species that is of such a dark colour. The under side 

 is not quite light enough, but it is a good approxi- 

 mation. This Mimeta is a rare bird, and may very 

 probably exist in Morty, though not yet found there ; 

 or, on the other hand, recent changes in physical geo- 

 graphy may have led to the restriction of the Tropido- 

 rhynchus to that island, where it is very common. 



Here, then, we have two cases of perfect mimicry 

 and two others of good approximation, occurring 

 between species of the same two genera of birds ; and 

 in three of these cases the pairs that resemble each 

 other are found together in the same island, and 

 to which they are peculiar. In all these cases the 

 Tropidorhynchus is rather larger than the Mimeta, 

 but the difference is not beyond the limits of varia- 

 tion in species, and the two genera are somewhat 

 alike in form and proportion. There are, no doubt, 

 some special enemies by which many small birds are 

 attacked, but which are afraid of the Tropidorhynchus 

 (probably some of the hawks), and thus it becomes 

 advantageous for the weak Mimeta to resemble the 



