352 TJniversitjj of California Publications in Zoology fVoL. 13 



pennular as well as basilar cells (compare plate 27, figure 53c with 

 plate 24, figure 47a). The proximal barbules, though resembling 

 the Galli in the diagonal line of conspicuous nuclei, differ in the 

 long, slender pennulum (pi, 27, fig. 5'3d). 



Psophia viridis, representing the Psophiidae, has barbules which 

 come very close to the peristeropode Galli, as will be seen by com- 

 paring plate 27, figures 54a, h, c and d with the figures of barbules 

 of Megapodius and Penelope (plate 24, figures 45a and h and 46a). 

 The iridescent golden green of a part of the outer vane of the 

 coverts is produced by refrangent barbules which are completely 

 metamorphosed to serve in color production. In form, on both 

 distal and proximal vanule, they are somewhat shortened, with no 

 barbicels whatever, as shown in plate 27, figure 54e. A short dis- 

 tance from their junction with the ramus they are bent suddenly 

 outward, and from this point, which is the widest, they taper 

 evenly to the tip. Both upper and lower surfaces refract light. 



Eurypyga helias, representing the Eurypygidae, also has bar- 

 bules which show an approximation to the type found in perister- 

 opode Galli, but show a more striking similarity to the Ardeae. 

 As shown in plate 27, figures 55a and c, the general form of the 

 distal barbules is remarkably like that of Ardea (compare plate 20, 

 figs. 20a and c), but the size and form of the ventral teeth and 

 ventral cilia are nearer to the megapodes. The proximal barbules 

 (pi. 27, fig. 55d) show a still closer similarity to the Ardeae in 

 the form of the base and in the slender filamentous pennulum, and 

 in the fact that no ventral cilia are developed on the proximal 

 barbules of the distal part of the barbs of the outer vane (com- 

 pare plate 27, figures 55& and d, with plate 20, figures 20& and d) . 



Cariama cristata, of the family Cariamidae, very much re- 

 sembles Eurypyga in the details of its feather structure, as shown 

 by plate 27, figures 56a and c, representing a distal and proximal 

 barbule respectively from a back feather. 



c) Down 



In Grus canadensis the down barbules are from 1.5 to 3.5 mm. 

 long, in the form of almost unmodified threads, which, however, 

 under high magnification show small prongs at the nodes, usually 

 two of unequal size, and appressed and inconspicuous. The barbules 

 show a tendency to scuff off, or become chafed, so that small frag- 

 ments may frequently be seen hanging froo them. 



