274 Mr. C. F. M. Swynnerton on the 



coloration of the mouths of nestlings is often of so striking 

 and fascinating a character, with its well-marked pattern 

 and its vividness comparable to those of eggs and of butter- 

 flies, that it is a matter for real wonder that so little 

 attention has been paid to it. A few cases, such as that of 

 the Gouldian Finch (Poephila mirabilis), have attracted 

 special remark, and led to an attempt at explanation. 

 Mr. CoUingwood Ingram, again, has given a summary of 

 a considerable number of interesting observations in his 

 paper "On Tongue-marks in Young Birds" ('Ibis,' 

 1907, pp. 574-578). 



Recently, Mr. Pycraft, in his ' Infancy of Animals,' 

 has discussed fairly fully the '^ more or less brilliantly- 

 coloured " mouths of nestling Passerines, as also the 

 significance and origin of the " ornaments " ; and this is 

 by no means his first or most important contribution to 

 the subject, for the " direction - marking " explanation, 

 undoubtedly applicable in certain cases, is his. But no 

 one, I think, has published so many detailed observations 

 on the subject as that admirable observer, Mr. G. L. Bates, 

 has included in his " Further Notes on the Birds of Southern 

 Cameroon-" (-Ibis,' 1911, pp. 581-631). My own obser- 

 vations, mostly long subsequent to his, and all subsequent to 

 Mr. Ingram's, were nevertheless, as accident had it, made 

 independently. I fear it shows how irregularly I have 

 studied my ' Ibis ' when absorbed in other work ! 



Family-characteristics. — One of the first things that strikes 

 the observer is the tendency to similarity between the 

 nestling-mouths of related species. I will take some of the 

 patterns in turn. 



1. The twin-spot tongue. Twin spots, vividly black 

 (usually, but in some birds paler), on or close below the 

 two basal spurs of the tongue. Background most usually 

 yellow or orange-yellow, but in some cases {e.g. White- 

 throat and Cisticola natalensis, fig. 6) of some other colour. 



The twin-spot tongue is essentially and primarily, 

 I believe, a Warbler characteristic. It is least intense, 

 according to Mr. Ingram, in Sylvia, but he has found it in 



