498 Mr. G. L. Bates on the 



in the forest, trusting to their stillness and the imperfect 

 light for protection. But they are not always silent, for 

 they make, at times, a very peculiar noise, which may be 

 described as a long-continued trilled " r " accompanied by 

 a voice-note, but is perhaps harsher than that description 

 would imply ; the adjective "grinding" has been appro- 

 priately applied to it. This noise is imitated by the natives 

 of this country by making the protruded lips vibrate while 

 uttering the note. It is evidently not a sound made with the 

 ordinary avian vocal organs used in the ordinary way. All 

 the species make this noise. It is made only while the bird 

 is in the air, taking a short circular flight from its perch 

 and back again, at the same time vibrating its wings rapidly 

 and displaying the white patch at other times hidden in the 

 plumage of its back. The whole performance seems well 

 calculated to be a mating-call and display of the male to 

 attract the female. When, drawn by the noise, which can 

 be heard at a distance, the mate approaches near enough, 

 she can see the white patch twinkling in the thicket, where 

 the bird would be invisible if sitting still. I have seen no 

 evidence that this noise is made by the female bird, and I 

 should consider this unlikely. Two birds, or even three, 

 that may often be heard, in different directions, answering 

 one another, are more likely riva. males. These grinding 

 calls are kept up at intervals of a minute or less, in early 

 morning and late evening, and sometimes at other hours on 

 dark days. I have never heard a bird of any of the species 

 of Smithornis make any other call or sound; but for a 

 reference to another cry made by *!5. cajjensis, see Mr. Claude 

 Grant^s account in 'The Ibis,' 1911, p. 422. 



In connection with the display of the white patch in the 

 back-plumage it may be added that the patch is present, 

 but small in females, and that it is absent in young birds. 

 Now will be given the promised anatomical facts. 

 Syrmx. — It was the peculiar noise made by the birds be- 

 longing to the genus Smithornis.^ and their apparent inability 

 to utter any kind of song such as most or all Flycatchers 

 sometimes utter, even though usually silent, that led me 



