260 University of California Publications in Zoology ‘Vou. 18 
acteristic black color being due to a uniform distribution of pigment, 
even in the prongs, thus differing markedly from the adults. The 
nestling down of Phalacocorax is hardly distinguishable from that 
described for the other water birds, some of the feathers being black, 
due to an even distribution of pigment in the barbs and barbules, a 
few remaining white. In gallinaceous birds, e. g., Dendragapus, the 
nestling down is not quite so primitive, the barbules being longer, 
with slightly swollen nodes and very inconspicuous prongs, but with 
evenly distributed pigment. 
From an examination of these few types, it may be safely con- 
cluded that neossoptiles show a much narrower range of modification 
in the minute structure of their down than do the teleoptiles, whether 
plumules or contour feathers. The fact that the structure of adult 
down in penguins is similar to the nestling down of not only pen- 
euins, but also of ducks, rails, and cormorants, may be an argument 
in favor of the primitive nature of the former birds. 
II. KFmoprLumMeEs 
1. Occurrence and Distribution 
Filoplumes are in some ways the most remarkable modifications 
of feathers found on birds. Although with a very few exceptions 
they are excessively slender and very difficult to see with the naked 
eye, and never developd in sufficient number to be of any possible 
mechanical use as a covering or support, these inconspicuous feathers 
are remarkably constant, in some degree of development, in all birds 
except the ratites. Nitzsch (1867) states that they are probably 
present in all birds, as he has never looked for them in vain, when 
the necessary trouble has been taken to find them. This statement, 
though generally accepted by ornithologists, needs further corrobora- 
tion. I have been unable to find them in the dried skins of a number. 
of birds, though they may have been present, but so reduced as to 
be very difficult to discern amongst the other feathers. Such an 
apparent lack of filoplumes occurred in two species of Pelecanus (P. 
erythrorhynchus and P. californicus), in Aechmophorus occidentalis, 
and other species. It may be stated positively that they are not 
present in ostriches or cassowaries, and probably not in any of the 
ratite birds. Nitzsch (1867) described filoplumes from cassowaries, 
stating that they were coarse, much flattened structures, very differ- 
ent from the filoplumes of other birds, and this has been widely 
quoted by other authors. Thorough examination of ostriches, both 
