  We report the completion of a survey of radio-loud AGNs begun in an earlier
paper, aimed finding and studying broad, double-peaked Balmer lines. We present
Ha spectra of 13 broad-lined objects (3 with double-peaked Ha profiles). The
final sample includes 106 radio-loud AGNs. 20% of the objects have Ha lines
with double peaks or twin shoulders and of these, 60% can be fitted quite well
with a model attributing the emission to a circular, relativistic, disk. We
also compare the Hb and MgII profiles of 4 objects with models of photoionized
accretion disks and find them to be in reasonable agreement. Double-peaked
emitters stand out on the basis of the following properties: (1) unusually
large contribution of starlight to the optical continuum around Ha, (2)
unusually large equivalent widths of low-ionization lines ([OI] and [SII]), (3)
unusually large [OI]/[OIII] ratios, and (4) Balmer lines on average twice as
broad as in other radio-loud AGNs. We evaluate models for the origin of the
lines and we find accretion-disk emission to be the most successful one because
it can explain the double-peaked line profiles and it also offers an
interpretation of the spectroscopic properties of these objects. Aternative
suggestions (binary broad-line regions, bipolar outflows, anisotropically
illuminated spherical broad-line regions) are unsatisfactory because (a) they
fail direct observational tests, (b) they cannot explain the unusual properties
of double-peaked emitters self-consistently, or (c) their physical foundations
appear to be unsound. We suggest that in double-peaked emitters and accretion-
powered LINERs the accretion rate is considerably lower than the Eddington rate
with the consequence that the inner accretion disk takes the form of an ion
torus and the wind that normally enshrouds the disk proper is absent.
