4. HKRODIAS. 89 



length of the tarsus is probably due to the immaturity of the 

 specimens, as it is extremely difficult to distinguish between young 

 birds and adults in winter plumage ; but it will be noticed that these 

 differences in the length of the tarsus occur in perfectly adult birds 

 in breeding-phimage, and, even allowing for a certain superiority 

 in the size in the male, the difference in the length of the tarsus 

 between the largest and smallest of the Indian birds must be 

 admitted to be enormous. The following is a summary of the 

 extreme measurements of the tarsus noted of the series in the 

 British Museum : — 



Summer plumage. Winter plumage. 



Southern Europe to in. in. in. in. 



Afghanistan 7-7o— 8-2 



Kashgar 6-8 —7-8 



Africa 5-4 —6-8 5-55— 6-8 



India 5-25— 69 53 —8-1 



Burmese Countries 55 — 6'4 '5-65 — 6'3 



China and Japan 5-9 5'4 — 6*6 



Malay Archipelago .5-35— 6-6 57 — 6-6 



Australia 5-2 —6-0 5-5 —6-0 



New Zealand 5-2 —6-4 



It will be noticed, in the measurements given below in the list of 

 specimens, that, on leaving out of consideration the extremely large 

 birds with the tarsus over 8 inches, we find that no Indian bird has a 

 tarsus of more than 7"5 inches. This certainly exceeds the length of 

 the tarsus of the smaller birds from Kashgar, which are supposed to 

 belong to the larger race. The bulk of Indian specimens, however, do 

 not reach 7 inches in the length of the tarsus. Burmese, Australian, 

 and New-Zealand birds apparently have 6'4 inches as the tarsal limit. 

 As, therefore, there seems to be a perfect gradation in the length of 

 the tarsus, which is shortest in Australian and New Zealand birds 

 (.5'2), and as much as S-2 in Indian and European examples, it is 

 difficult to found any worthy distinction on the tarsus ; but the 

 colour of the bill and tibia appears to me, as it did to Mr. Eidgway, 

 to offer a character by which the different races can be distinguished. 

 I have considered the African specimens of the Great White Egret 

 to belong to the same race as the European and Indian bird, which 

 has the bill black in summer and yellow in winter. The African 

 specimens examined by me have all had yellow bills and black 

 tibiiB ; but as none of them have been in full summer plumage, I must 

 wait for further material before being able to decide that the 

 African bird has a black bill in summer. Erom the remarks here 

 given, and those which follow under the headings of the species 

 themselves, it will be seen that the identification of the Great 

 "White Egrets requires a prolonged study. 



Taking the breeding-plumage only, we have the following 



Key to tJie Sjjecies. 



jtt. Bill black in summer, yellow in winter ; tarsi 

 and tibiaj black in winter, the latter flesh- 

 coloured in summer alba, p. 90. 



