Oology

Yet it is not difficult to see that Oölogy promises to become an important auxiliary both in aiding to determine natural divisions, and to enable us to decide in regard to varieties the specific identity of which is in doubt. Let us take an instance. [...] Without looking at all to the external structure of these birds, Oölogy would seem to indicate that the Cat-Bird, though closely allied to the true Mocking-Bird, is at least one step, and that the Brown Thrush is even farther, removed.

Source: wiktionary

Now here is just one of those cases, which bring the study of Oology, and very justly, into more discredit than any other thing. M. [Alfred] Moquin-Tandon's egg is very likely that of a Booted Eagle; but where is the proof of the fact? Absolutely, as we read it, there is none. [...] There are many collectors in this country, who yearly spend large sums in buying eggs from dealers—utterly un-identified, or with (since identification of eggs has lately become somewhat fashionable) a plausible history, but one that will not bear investigation.

Source: wiktionary

A short sketch, such as Mr. [Cholmondeley] Pennell's, of the economy of the Bird, would be a most valuable addition to our ordinary ornithologies and oologies. He said oologies, for even in the egg of the bird the special needs of the forthcoming bird seemed to be more especially provided for than in the eggs of other families much higher in the scale.

Source: wiktionary

When we come to examine the oölogy of the great Columbo-gallinaceous group, one well represented in the avifauna of the United States, it is possible to make the comparisons quite extensive, owing to [Charles] Bendire's exhaustive labors, as seen in his fine quarto volume already spoken of at the beginning of this paper.

Source: wiktionary