  We selected 115 extremely red objects (EROs) from deep HST WFPC2 archive data
combined with ground-based K-band images, with (F814W - Ks) >= 4mag, K-band SNR
>= 5, and a median limiting Ks magnitude of 18.7mag, over a corresponding area
of 228 sq. arcminutes, for a morphological study of the ERO galaxy population.
The survey covered a total of 409 sq. arcminutes over 77 separate WFPC2 fields.
This is the first complete sample of bright EROs with high resolution HST
morphologies. From a visual morphological classification, we find that 30+/-5%
of our EROs have morphologies consistent with a pure bulge or bulge-dominated
galaxy (equivalent to E/S0), while disks comprise 64+/-$7% of the sample. Only
6% of the EROs remained unclassifiable. Mergers or strongly interacting
systems, which includes sources from both classes, make up 17+/-4% of the full
sample. The quantitative MDS profile fitting is consistent with these results.
These results highlight the complex nature of optical/near-IR color selected
EROs. The dominant component of our sample is comprised of disks, not spheroids
or strongly interacting systems like HR10. Using Bruzual & Charlot SED models,
we investigated population differences in EROs selected by their (I-K) vs.
(R-K) colors and found that I-band based surveys preferentially select systems
with prolonged star formation. Real differences in the surface densities of
EROs in R-band and I-band based surveys may reflect this color selection
effect, complicating the comparisons between and interpretations on the nature
of the ERO population. <Abstract truncated>
