164 
THE CONDOR 
Vol. XVI 
the ducks and auklets, while specimens from Florida would be located at the 
bottom, congenially surrounded by spoonbills and limpkins ! To my way of 
thinking the oologist who, with a given amount of time (and money) starts out 
to illustrate all that is ascertainable about the nidification of, say, our North 
American Icteridae, can accomplish far more in the way of scientific results 
than by attempting to accumulate a “set” of every known form on the A. 0. 
U. List. 
While the number of problems open to investigation by the intensive 
study of a group collection is almost endless, the inviting road towards broad 
generalizations is far less easy than it seems ; for on every hand there is abund- 
ant opportunity for false and hasty conclusions which will inevitably carry us 
far afield. Hence, the systematists are prone to complain that we can afford 
them little assistance in their labors, as likeness or dissimilarity in birds’ eggs 
cannot generally be relied upon to indicate a corresponding degree of relation- 
ship among the birds themselves. Let us cheerfully admit it, proceed to show 
wliere the correspondence begins and ceases and then, if possible, ascertain 
u'hy. But in many eases the correspondence is really very close ; such exam- 
ples as those of the owls, tinamous and shore-birds will occur to all, and it is 
said that the relationship of this last group to the gulls and terns was first 
l)ointed out by oologists. Even small groups are sometimes sharply defined, 
such as the peculiar markings characteristic, I believe, of the genus Myiarclrtis. 
On the other hand, the many exceptions, while difficult and confusing, are 
no less interesting and would doubtless prove equally informing if we held the 
explanatory key. Thus, eggs of the herons are greenish, while those of the 
slightly differentiated bitterns may be nearly white or decidedly brown, but 
are still unspotted. Among their allies, the ibises and spoonbills, however, 
variation runs riot and we find plain white (e. g., Ihis molucca), light greens, 
dark greens and spotted types in great diversity. Such examples become par- 
ticularly puzzling when we observe that certain species, even more closely al- 
lied, occupying the same restricted habitat, and having identical methods of 
uidificaton, may yet produce eggs extremely unlike; as an American example 
compare the Avhitish, spotted eggs of Toxostorna bendirei with the plain, green- 
ish specimens of its neighbor, T. crissalis. 
It is particularly in the investigation of such facts that the group collec- 
tion, of restricted scope, should be of value. Suggestive facts may be forth- 
coming; thus, if we consider the eggs of the Mimidae as a whole we find that 
Avhile nearly all are commonly spotted, those that are plain (e. g., T. crissalis, 
G. carolinesis) seem to always adhere to that type, while in the other fonns 
there is an occasional tendency to lightly marked or unmarked examples. Let 
us contrast this with an illustration from the genus Accipiter; eggs of fuscus 
and nisus are, typically, richly marked, those of cooperi are commonly plain, 
while specimens of cirrlwcephalus (Australian) in my collection are intermedi- 
ate. But I have one set of cooperi (taken by Bingaman) which shows about as 
much superficial coloring as average specimens of B. borealis, while eggs with 
a few faint spots are not uncommon. Apparently in the genus Accipiter either 
the habit of laying plain eggs has not yet become fixed in any species, as it has 
with some Mimidae, or, more probably, I think, the habit of laying colored 
eggs has been newly acquired and is not yet universal. We cannot say positive- 
ly, yet it does seem as if in certain groups we could trace indications of a 
progressive increase or decrease in egg-pigmentation, which is actually in pro- 
