of a Typical Pennaceous Feather. 433 



barbules were cut off by placing a sharp razor on the 

 sides of the barb and pressing gently on the slide, 

 when sufficient perfect barbules of each kind were 

 obtained for examination. 

 (3) Portions of the vane were carefully embedded in paraffin, 

 and sections cut and mounted by the kreosote-shellac 

 method, so that the parts were obtained in their 

 relative, natural and undisturbed, positions, 

 (a) . Transversely : i. e., at right angles to the long axis of 



the barb). 

 {h) Horizontally : «. e., parallel to the surface of the vane. 

 (c) Oblique sections in directions parallel to the distal 

 barbules {cf. fig. \a, a to /3). Some of these 

 showed the barbs in oblique section, a distal 

 barbule quite perfect, and sections of the proximal 

 barbules. In these could be seen exactly how the 

 booklets cling to the flange {cf. fig. 4). 

 Drawings were then made of all the parts in every position 

 from these working-drawings, and the model produced in 

 gutta-percha. 



EXPLANATION OF PLATE XIL 

 B, barb ; hd, distal barbule ; and bp, proximal barbule in all figures. 



Fig. 1. Perspective view of portions of two adjacent barbs looking fi'om 

 the main stem towards the edge of the feather. 



Fig. la. Diagram of surface view, a to j3 direction of oblique sections 

 described in text. 



Fig. 2. A proximal barbule. 1, flange ; 2, " dog-tooth " part of flange ; 

 3, overlapping portion. 



Fig. 3. Diagrammatic view of a barb from above, a, slightly magnified • 

 /3, more highly magnified ; 3', the apparent firm edge parallel to 

 barb. B shows its composition, 1, 2, 3 as in fig. 2. 



Fig. 4. Oblique section in direction a to /j (fig. !«), showing the exact 

 manner of the interlocking of the barbules. 1, tooth-like pro- 

 cesses ; 2, hooked barbicels ; 3, unhooked barbicels : 4, pro- 

 cesses serial with 3. The proximal barbules, bp, are seen in 

 oblique section. 



