1893 THE INTERLOCKING OF FEATHERS. 201 



leave us in a little uncertainty as to whether the full extent of the 

 curvature of the radii is appreciated or not. Thus (quoting Klee) he 

 says, " Ihr oberey Rand^ ist einfach umgeschlagen, wodurch langs dieses 

 Randes eine vollkommene Rinne zu Stande kommt, die unter dem 

 Mikroskop allerdings den Eindruck eines verdickten Randes niacht." 

 And again, speaking of the elasticity of the feather, he says, 

 " Zugleich ist die Fahnein hochsten Grade elastisch, nicht nur durch 

 die Elasticitat aller einzelnen Federtheile, sondern well die Hacken 

 auf den glatten Strahlen Kanten^ hin — und hergleichen konnen." 



The relative position of the radii, like their form, varies. Both 

 distal and proximal rows may arise from what would otherwise be 

 the ridge of the ramus, or the distal radii may arise from the upper 

 border of the ramus, while the proximal may run along quite near 

 the lower border. Frequently the distal radii are overhung by a pro- 

 jecting ledge, formed by the much compressed ridge of the ramus, 

 and between these every possible gradation may be found, according as 

 the part examined be from the primaries, secondaries, or coverts, or 

 from the inner or outer margins of the vexillum. 



Along the lower edges of the rami in Fig. 2 will be noticed a 

 thin transparent band (p) of a width corresponding to the section. This 

 I recently found in the remiges of a Teal, Qneyqnedula cvecca. The free 

 edge may be either closely approximated to, or even fused with, the 

 lower edge of the next ramus. To the naked eye, this appears along 

 the side of the shaft as a narrow band of silvery whiteness, and very 

 smooth, but I am at a loss to account for its function, and do not care 

 to hazard a guess. I have indicated the presence of a similar band 

 under the proximal radii ; it seems, however, to occur but rarely. 

 Mr. R. S. Wray, to whom we shall have occasion to refer presently, 

 makes mention of such a band in his paper, shortly to be noticed. 



I propose now to present a sort of census of opinion as to how the 

 " Interlocking of the barbs of a Feather " was obtained; but, to be 

 brief, it will be well to confine attention to the descriptions of some 

 three or four writers whom we may consider to have been more or less 

 well-qualified to speak on this subject. This will carry us back some 

 sixty years, to the time of the great Nitzsch, the father of the science 

 of Pterylography. His description was fairly accurate ; the wonder is 

 it was not quite so. He perceived that the radii could be divided 

 into two series — an anterior and a posterior, as he called them, but 

 he failed in his endeavour to explain their mutual relations, consider- 

 ing that the hamuli of the anterior radii were for the purpose of 

 catching into " little pits " prepared for their reception in the 

 proximal radii. Burmeister, editing Nitzsch's work a few years later, 

 exploded this theory, and gives essentially a correct explanation. He 

 says, " I have noticed in all parts a strongly-thickened, superior 

 margin of such a size that the hooklet can just grasp it. It is behind 

 this margin .... that the hooklets take hold." 



- The italics are mine. 



