  We report on the neutral hydrogen gas content (21-cm emission) of eight
extremely isolated early-type galaxies (IEGs) using the Green Bank Telescope.
Emission is detected in seven of the eight objects. This paper is the third in
a series that collectively present new HI observations for 20 IEGs. Among the
14 HI detections in our observations, eight exhibit a Gaussian-like HI line
profile shape, four are double-peaked, one is triple-peaked, and another has a
plateaued rectangular shape. Five additional IEGs observed in previous surveys
were added to our analysis, bringing the total number of IEGs with HI
observations to 25. Of these objects, emission is detected in 19 (76%). The 25
IEGs in our combined study have gas masses that are systematically larger than
their luminosity-matched comparison galaxy counterparts. The isolated
early-type galaxies presented here follow a trend of increasing gas-richness
with bluer B-V colors. This correlation is also observed in a comparison sample
drawn from the literature composed of loose group and field early-type
galaxies. Two IEGs, KIG164 and KIG870, exhibit properties highly anomalous for
spheroidal systems: luminous (M_B = -20.5, -20.1) and blue (B-V = 0.47, 0.48)
respectively, with substantial neutral gas, M_HI = 4.1 & 5.5x10^9 M_(sun).
Other IEG systems may represent early-type galaxies continuing to assemble via
quiescent HI accretion from the cosmic web or relaxed merged systems.
