286 Transactions.— Zoology. 



versy. It has always appeared to me that it might not be 

 altogether a subject in the domain of mathematical physics, as 

 has been assumed, but rather that it might be a difficulty for 

 the anatomist to solve with his scalpel. In 1871 I made some 

 attempts, assisted by my friend Sir Walter Buller, to dissect, 

 after injecting the arteries and veins, the wing of the albatros; 

 conjecturing that, as such birds are rarely obtained in the flesh 

 in the Northern Hemisphere, some structural differences might 

 have escaped notice. We were not very successful on that 

 occasion, excepting that I believe we discovered that the long 

 tendon extending from the extensor muscles that control the 

 folding-up and expansion of the wing {extensor plica alaris) 

 terminated in tendinous fibres which, supplemented by mus- 

 cular fibres, grasped the quills of the large pinion-feathers, 

 and might perhaps impart to them a reciprocal motion like the 

 feathering of an oar. 



It was difficult to conceive how these muscles could per- 

 form two such difficult functions as were involved in the 

 expansion of the wings as a whole and at the same time to 

 exercise a control over its distal appendages. I was therefore 

 not surprised when the result of the dissection of several fine 

 specimens in the flesh preserved in spirit, and which I sub- 

 mitted through Sir Walter Buller to authorities in London, 

 pronounced against there being any anatomical structure 

 present. 



Lately I have had an opportunity of re-examining the wing 

 of a large albatros in the flesh, and find the following peculiari- 

 ties, which, so far as I know, have not been hitherto recorded : 

 The extensor muscular tendon, instead of being attached as in 

 other birds only to a fixed process at the distal extremity of the 

 humerus, is also attached by a subsidiary offset to a projecting 

 patelloid bone which is articulated with the process, and thence 

 proceeds to the radial carpal bone, and thence onward along 

 the radial aspect of the manus, where it expands into fibrillae 

 that embrace the quills. When the wing is fully extended 

 the thrust of this projecting process on the elbow-joint causes 

 a slight rotation of the ulna on the humerus, so that the 

 joint becomes locked, which renders the wing a rigid rod as 

 far as the wrist-joint. At the same time the slight play per- 

 mitted by the articulation of the patelloid bone on the process 

 allows of the transmission of the muscular pull from the 

 shoulder to the manus without unlocking the joint. By this 

 mechanism the sustaining diameter of the bird is enormously 

 increased without any increase of weight. In an albatros of 

 ordinary size the rigid surface presented to the atmosphere 

 like a parachute would have an extension of 10ft. Beyond 

 this on either side is the true efficient pinion of the bird, 

 erroneously called the tip of the wing, which, as all who have 



