260 University of California Publications in Zoology [Vol. 13 



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- 

 guins, but also of ducks, rails, and cormorants, may be an argument 

 in favor of the primitive nature of the former birds. 



II. FiLOPLUMES 



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. 

 erythrorJiynchus and P. calif ornicus) , 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 



