352 University of California Publications in Zoology |Vor. 18 
pennular as well as basilar cells (compare plate 27, figure 538c 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 (pl. 27, fig. 53d). 
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, b, c and d with the figures of barbules 
of Megapodius and Penelope (plate 24, figures 45a and b 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 
(pl. 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 55b and d, with plate 20, figures 20b 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 from them. 
