Description of the Modifications of certain Organs. 635 



time of its life in an oblique and lopsided position whilst examining 

 the stony ground in search of food, thereby turns the left side of its 

 head and neck towards the ground, and thus hides the conspicuous 

 spot, whilst the right side is exposed to the view of enemies and 

 consequently cannot by natural selection be permitted to develop so 

 fully. However I do not feel incliued to favour this latter view, and 

 bave given it only as a possible Suggestion. The bird whilst sleeping 

 will by the very configuration of its bill put the latter over its right 

 Shoulder, and will then fully expose the broad portion of the collar; 

 hence I conclude that the patch is ornamental as well as protective, 

 in other words that it is meant to be seen. 



At any rate it seems reasonable to consider the asymmetry of 

 the bill to stand in correlation with that of the plumage, that the 

 former is the priraary and the latter the secondary modification. The 

 interdependence between two so widely ditferent characters, as shape 

 of bill and colour of plumage, indicates again the very old and an- 

 cient nature of this abnormally shaped bill, and explains its early 

 repetition in the young birds, long before they would be able to bend 

 their bills invariably to the right side. 



3. The tracheal labyrinth of the Ducks. 



The following communication refers to an Observation made by 

 "Wunderlich^) on the well known bullae or labyrinthic swellings of 

 the syrinx of the male Ducks. He examined the embryos of more than 

 30 Ducks and found that the future labyrinth (leftsided in the com- 

 mon drake) was already indicated , in embryos from 3—20 days of 

 incubation, by a swelling on the left side, and was on about the 10 "* 

 day formed by 4 rings which were thicker and broader than the rest. 

 This dilatation persists in the males but in the females it undergoes, 

 from about the 27 "■ day of incubation, a retrogressive metamorphosis, 

 and disappears before the bird is hatched. 



Owing to want of material I have not been able to examine this 

 point rayseif, but to judge from the painstaking way in which Wun- 

 derlich's paper is written and illustrated, we have no reason to 

 doubt the accuracy of his Observation, especially as he was fully aware 

 of its importance. 



1) L. WuNDEELiCH, Beiträge zur vergleichenden Anatomie des 

 unteren Kehlkopfes der Vögel, in : Nov. Act. Kaiserl. Leop.-Carol. Deutsche 

 Akademie der Naturforscher, Bd. 43, 1884. 



