150 correspondencp: of ray. 



admitted to our tables. I observed in this bird, and in 

 some others of the sea-diicks, which are much under 

 water, that they want that vessel, or ampulla, situate in 

 the very angle of the divarication of the windpipe, which, 

 for want of a better and fitter name, we are wont to call 

 the labyrinth of the trachea; which, though being common 

 also to the Colymhi, which of all bu'ds dive most and con- 

 tinue longest under water, we may very probably from 

 thence conclude that the labyrinth doth not serve them for 

 a reservatory of air, to enable them to continue the longer 

 under water, as I sometimes conjectured, but for the 

 intending or modulating of the voice, seeing i]i the plash- 

 ducks the females want it. But I am somewhat to seek 

 about the use of this vessel, and I tliink it were worth 

 the while to examine what sorts of birds have it, what 

 want it ; and in those sorts that have it, whether the 

 males onlv, or in some the females also. I observed it in 

 the Mergus cirrafics longiroster major, or the Dun-diver 

 \_Me)yus serrator], and that very large and extended by 

 very strong bones ; and yet I thought myself to have suf- 

 ficient reason to judge that l)ird to be the female of the 

 Merganser [Merj/us serrafo)-] ; but I dare not be confident 

 that it is a female, because of this labyrinth. And now that 

 I am writing of birds, I propose it to your consideration, 

 whether that sort of bird, mentioned by Dr. Plot to be often 

 heard in Woodstock-park, from the noise it makes, com- 

 monly called the V^oo&c]L?ic\iex\_Wood hacker, Woodpecker'], 

 be not the lesser sort of Picus martius varius? For since 

 the pubhshing of Mr. Willughby's ' Ornithology,' I have 

 observed that bird sitting on the top of an oaken tree, 

 making with her bill such a cracking or snapping noise, 

 as we heard a long way off, the several snaps or cracks 

 succeeding one another with that extraordinary swiftness 

 that we could but wonder at it ; but how she made the 

 noise, whether by the nimble agitation of her bill to and 

 fro in the rift of the bough, or by the swift striking of the 

 mandibles one against another, as the stork doth, I cannot 



