262 ALLEN'S NATURALIST'S LIBRARY. 



short hiss, when bullying some other bird or fighting amongst 

 themselves, but, he adds " I have heard occasionally on the 

 coast of North Wales at night a somewhat Wigeon-like whistle 

 that emanated, as I believe, from ' Sand-Geese ' on the wing." 



Nest. Composed principally of the bird's own down, with a 

 few leaves occasionally, as mentioned above by Mr. Robert 

 Read. In some parts of Denmark the peasants make artificial 

 burrows for the birds, and systematically rob the nest, as many 

 as thirty eggs having been taken from one burrow in a single 

 season. 



Eggs. From seven to twelve in number, but sometimes as 

 many as sixteen have been found. They are dull creamy- 

 white, with very little gloss. Axis 2 '45-2 '6 inches ; diam., 

 i -8-1-95. The down is ashy-grey, with silvery white ends, 

 and with a few white feathers intermingled. 



THE RUDDY SHELD-DUCKS. GENUS CASARCA. 

 Casarca, Bp. Comp. List B. Eur. & N. Amer. p. 56 (1838). 

 Type, C. casarca (L.). 



The members of the genus Casarca, according to the conclu- 

 sions of Count Salvador!, differ from the typical Sheld-Ducks 

 (Tadornd) in the following characters : The bill does not 

 widen towards the tip, and is no broader at the tip than it is at 

 the base; the culmen is almost straight; the lamellae are 

 equally developed along the inner edge of the upper mandible, 

 and the lamellae on the edge of the lower mandible project 

 outwardly ; the bill and feet are dark, and the sexes generally 

 differ in colour. 



Four species of the genus Casarca are known, C. casarca, 

 C. cana from South Africa, C. variegata from New Zealand, 

 and C. tadornoides from South Australia and Tasmania. In 

 the Ruddy Sheld-Duck, where the sexes are alike, there has as 

 yet been no proof of any change of plumage in summer, such 

 as occurs in most species of ducks. The post-nuptial plumage 

 is probably emphasised by the loss of the black collar. In 

 the three other species, however, where the sexes are different 

 in colour, the male doubtless undergoes a change, as Mr. 

 Blaauw has noticed a double moult in C. tadornoides. 



