SUBFAMILY CHRYSOMYINAE 181 
Onesia. The accuracy of the determinations by these authors 
cannot now be established. It is probable that Banks (1912) had 
sialia. Many of Walton’s specimens reported upon in 1915 have 
not been located, but those that are in the National Museum are 
sialia and hirudo. | 
~The species of Apaulina are well distributed throughout the 
northern part of the United States and southern Canada. At 
least one species occurs in Alaska; but no species of Apaulina has 
been noted south of Virginia. In response to a request for such 
information several southern ornithologists have stated that they 
have never observed nests of birds infested with species of 
Apaulina. In addition Mr. H. J. Reinhard, Entomologist, Texas 
Agricultural Experiment Station, informs me that there are no 
southern specimens of Apaulina in either his collection or that 
of the Texas Experiment Station. It would appear that some 
of these parasites should occur considerably further south in the 
United States than the present records indicate; many of the 
species of birds in the following list nest as far south as Arkan- 
sas. For instance, the yellow-breasted chat, which may appear as 
early as April 10 in northwestern Arkansas, nests frequently 
in that area. 
It is obvious that the forms of Apaulina are very closely re- 
lated taxonomically and biologically. Some of the species are so 
close that they can be separated only with considerable difficulty. 
Different species are often reared from a single nest and such 
series may not always indicate a proper association of the 
sexes if different but closely related species are involved. Our 
knowledge of the taxonomy of the entire group is especially 
restricted by the lack of specimens from known strains. The 
present study has been made from series of specimens reared 
from nests of birds or from specimens collected in the field in 
hand nets, and it is impossible to know the range of variation 
within a single species or whether diversity considered of specific 
value in this study is genetic or caused by ecological conditions. 
The first segregations made in this study were based princi- 
pally upon the differences in the male genitalia; differences in 
head structure were then correlated with these. Additional 
specifie differences were found in chaetotaxy in several instances, 
or, finally, color differences were utilized as supplementary char- 
acters for the separation of the species. 
There are apparently three species groups of Apaulina in 
North America. The first includes aviwm, basingert, and perhaps 
sapphira which apparently belongs here on head structure 
although the genital structure is similar to that found in metal- 
