292 R. M. STRONG. 



the usual manner. The shaft of the main portion of the feather 

 is not continuous, however, with the shaft of the distal ap- 

 pendage. The distal ends of the barbs nearest those actually 

 fused with the horn cylinder have strips of horn tissue (Fig. 5, <?.), 

 which seem to have been torn loose from the cylindrical mass 

 with which they were probably fused in the feather germ. 



Near the points where the barbs fuse with this horn cylinder, 

 the barbules are less highly differentiated. The most distal 

 barbules are comparatively irregular strips of keratin which may 



1..CJL 



- 



FIG. 4. FIG. 5. 



FIG. 4. Dorsal view of a normal body covert from the back immediately anterior 

 to the upper tail coverts. X 2 - 



FIG. 5. Dorsal view of an abnormal body covert from a region corresponding to 

 that furnishing the feather shown in Figure 4. cyl., horn cylinder; a, position of a 

 fragment torn from horn cylinder. X 2 - 



be fused at their distal ends with the cylindrical mass, as can be 

 seen in Fig. 6 where two barbs and a barbule are shown fusing 

 with a strip of tissue torn from the cylinder. 



Discussion and Conclusions. - - It is significant that these abnor- 

 malities occur at uniform distances from the distal ends of the 

 feather throughout the whole plumage, and it seems reasonable 

 to conclude that the conditions responsible for the abnormalities 

 were constitutional, and affected the germs of all the feathers 



