96 Mr. C. Boden Kloss on Birds [Ibis, 



synoQym), leaving available for tbe northern form the 

 name amb'iguus given by Hartert to birds from the Malay 

 Peninsula, Burma, Assam, and the Eastern Himalayas. 

 (The first-named place must be regarded as the typical 

 locality ; but it is a rather comprehensive term, and as 

 I suspect Hartert meant by it all the country south of 

 about lat. 13° N., I would restrict it for the sake of greater 

 preciseness to the southern part of Tenasserim.) 



I have before me a series of birds ranging through tlie 

 Malay Peninsula from Siara to Singapore, and their wing- 

 liieasurements are so variable that it seems impossible to 

 strike a difference between northern and southern examples 

 in this respect : — 



Koh Lak, S.W. Siam ISO. 



Trang, Peninsular Siam 194, 190, 186, 186. 



Langkawi Id., Kedah 1 94. 



Treugaunu, Malay States .... 177 (apparently adult). 



Peuang- Id 187. 



Pahang, Malay States 193! 



Perak, „ , 193,180. 



Selangor, „ „ 196, 193, 193, 193, 191, 190, 190, 



189, 188, 187, 185, 185. 



Singapore Id 181, 188, 186. 



It will be seen that Singapore examples are no smaller 

 than several more northern birds ; and it remains to be 

 shown if an equal series from that island will include 

 longer-winged examples or not. 



On laying the series out from north to south one gets the 

 impression, however, that the buft'y markings on the back 

 and wings of southern birds are of a deeper, richer tint than 

 is the case with northern specimens : this is not always so 

 with individuals, but one seems to see a difference, though 

 very slight, with series. The point where change takes 

 place is about the latitude of Penang, and so I suggest that 

 birds from the south of this, including Sumatra, should be 

 known as bimacalatus, while northern birds should be called 

 ambiguus. Of course, if this distinction prove fallacious 

 and a difference cannot be established, all should stand as 

 bimaculutus Peale. 



