630 DK. P. CHALMERS MITCHELL ON THJ; [Dec. 17. 



has placed material (some of it belonging to the Society, and some of 

 it his own) at my disposal. I have actually dissected the following 

 forms : — 



Rallicbe .... Aramides cayennensis. 

 ,, ypecaha. 

 FtiLiea leucoptera. 

 Oallinula chloroj>us. 



,, phosnicurug. 

 Hypota nidia phUipjpensig. 

 Porzana Carolina \ 

 Ballus celebensis. 

 „ lonffirogtris. 

 „ maculatug. 

 Gruidae .... Balearica chrysopdargus (Gruinae). 

 Aramus scolopacevs (Araminae). 

 Psophia leucoptera (Psophiinae). 

 obscura (id. I. 

 Dicholophidar. Cariama cristata. 

 Otididae .... Otis tarda. 

 Ehinochetidaj. Ehinoehetus jubatug. 

 Eurypygidac. . Ewyjyyga Julias. 

 Heliornithida?. Heliornig fuliea (sen Podoa suHnamensis). 



J Lave, moreover, made full use of the published observations 

 o£ Beddard (1), Gadow (4). and Fiirbringer (3) on these and 

 allied forms, but any detailed statements which 1 make in this 

 paper I have myself observed or verified unless I cite them on the 

 authority of their author. 



The direct object of the enquiry the results of which are now to 

 be set out, was a prosecution of investigations to which my 

 discovery of the eutaxy in the wing of certain Pigeons (8) led me. 

 I came to the conclusion that in the Columbidae the diastataxic 

 condition of the wing was primitive, and that the eutaxic condition 

 was derived therefrom by a secondary closing up of the diastema 

 in the ranks of feathers. I found that there was a general 

 coincidence between the specialized condition of the wing and 

 specialized conditions of other anatomical structures, and a similar 

 general coincidence between the primitive condition of the wing 

 and less specialized conditions of other anatomical structures. 

 Later on I studied the structure of Kingfishers, a group in which 

 the occurrence of both conditions of the wing was known, and I 

 was able to show (9) that also in that group there existed a 

 correlation between specialization of the wing and specialization of 

 other anatomical structures. In a later memoir (10) dealing with 

 the modifications presented by the Alimentary Canal in the whole 

 group of birds, I had occasion to employ a precise terminology for 



1 Beddard (1) states that P. Carolina is exceptional in having a nude oil- 

 gland ; in the specimen I examined the gland was definitely tufted, and the 

 same was true of some chicks that 1 examined along with Mr. Pycraft at 

 the British Museum. 



