180 CLANGULA CHRYSOPHTHALMA. 



twelfths in \A-idth, but toward the end enlarged to four- 

 twelfths, and rounded. 



Variations. — In adult individuals examined in winter, 

 the differences are not generally very remarkable. The 

 males differ considerably in size, from eighteen to twenty 

 inches in length, from thirty to thirty-four in extent of wing. 

 The bill is stouter, higher, and broader at the base, appa- 

 rently in proportion to the age of the individual. The fea- 

 thers of the head are much longer in some than in others ; 

 and in some the first quill is longer than the second, in others 

 equal, but generally, I think, the second is the longest. The 

 gi-een feathers extend farther down the neck in some than in 

 others, there being a difference of an inch in this respect. 

 The white spot on the fore part of the cheek varies in form 

 from roundish to oval, or even oblong. Although the large 

 white space on the wing is continuous in all the specimens 

 which I have seen excepting one, it is in it divided by a 

 transverse narrow black band. In that individual, shot late 

 in spring, the feathers are considerably worn on the neck, 

 and the partial appearance of the black of the white-tipped 

 secondary coverts seems to be owing to the abrasion of the 

 tips of the white feathers lying over them. Females differ 

 somewhat in size, and slightly in colour. The intestinal canal 

 varies some inches in length in both sexes, and the enlarge- 

 ments of the trachea may be more or less ossified, and are 

 variable in extent, though not so much in form. 



Habits. — I have not met with individuals of this species 

 beyond the beginning of May, although I have then seen 

 them in pairs in the Island of Harris, always on small fresh- 

 water lakes ; nor does it appear that any have hitherto been 

 found breeding in Scotland, or even in the Shetland Islands. 

 Like most of our Ducks, they betake themselves to the arctic 

 regions, whence they return in autumn, making their appear- 

 ance in the beginning of October, and continuing to increase 

 in number until the winter has fairly set in. During winter 

 they are met with in all parts of the country, from Shetland 

 and Orkney on the one side, and the Lewis Islands on the 



