370 Mr. W. Thompson on the Occurrence of a Surf Scoter. 



teriorly. Under mandible white, except towards the nail, where 

 it is orange ; nail a mixture of white and brownish orange. Legs 

 and toes deep red, inclining a little to orange, and blotched more 

 or less with black ; this latter being the colour of the webs and 

 nails, with the exception of one nail, which is white. 



A very full description of the trachea of the Surf Scoter, with 

 measurements of the different portions, is given by Audubon 

 (vol. iv. p. 166), who correctly remarks, that it presents the same 

 structure as that of the Velvet Duck [Old. fused). 



The specific differences however seem to me worthy of being 

 figured — which in so far as I am aware has not yet been done — 

 and for that purpose I have made a drawing of the 

 trachea of the present specimen. This, for the sake 

 of comparison with that of the Velvet Duck figured 

 by Yarrell, has been drawn on the same scale. It 

 will be seen from my figure, that the Surf Scoter, 

 as well as the species just named, exhibits within 

 the upper expansion of the trachea " an aperture 

 on each side," &c, as particularly noticed in the 

 case of the Velvet Duck by Mr. Yarrell (B. B. vol. 

 iii. p. 219, 1st edit., or p. 316, 2nd edit.). 



in. 



Length of trachea of Surf Scoter (see figure) \ , 

 from a to a / 



Breadth of trachea at b 



Length of enlargement marked c I 



Breadth of enlargement marked c 1 



Length from the "base of the lower enlarge- "| 



ment to the origin of the two inferior tubes 9 

 —marked d J 



Length of fleshy process marked e 3 



Length of fleshy process marked / 11 



Although the peculiar form of the trachea, as 

 well as the external characters, generally place 

 this species next to the Velvet Scoter, yet in the 

 form of the bill the two species differ very considerably. This 

 difference has been admirably pointed out by Mr. Selby in the 

 following words : — " In this species [Oid. perspicillatd] the 

 bill has not that flatness and expansion in front of the nostrils 

 that are so conspicuous in Oid. nigra and Oid. fusca, but 

 assumes, in a great degree, the characters of the succeeding 

 genus Somateria (Eider), by the tip being suddenly contracted, 

 and the nail (which is also more convex than in the other spe- 

 cies) being brought to a narrow rounded point ; the entering 

 angle of the forehead also projects, as in the common Eider, as 

 far as the nostrils. The lateral parts of the bill at the base are 

 very tumid, and are particular from the marking there displayed, 

 these swellings being entirely exposed, and not in part concealed 



lin. 







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