  We report an analysis of the interstellar gamma-ray emission from the
Chamaeleon, R Coronae Australis (R CrA), and Cepheus and Polaris flare regions
with the Fermi Large Area Telescope. They are among the nearest molecular cloud
complexes, within ~300 pc from the solar system. The gamma-ray emission
produced by interactions of cosmic-rays (CRs) and interstellar gas in those
molecular clouds is useful to study the CR densities and distributions of
molecular gas close to the solar system. The obtained gamma-ray emissivities
above 250 MeV are (5.9 +/- 0.1(stat) (+0.9/-1.0)(sys)), (10.2 +/- 0.4(stat)
(+1.2/-1.7)(sys)), and (9.1 +/- 0.3(stat) (+1.5/-0.6)(sys)) x10^(-27) photons
s^(-1) sr^(-1) H-atom^(-1) for the Chamaeleon, R CrA, and Cepheus and Polaris
flare regions, respectively. Whereas the energy dependences of the emissivities
agree well with that predicted from direct CR observations at the Earth, the
measured emissivities from 250 MeV to 10 GeV indicate a variation of the CR
density by ~20% in the neighborhood of the solar system, even if we consider
systematic uncertainties. The molecular mass calibrating ratio, Xco =
N(H2)/Wco, is found to be (0.96 +/- 0.06(stat) (+0.15/-0.12)(sys)), (0.99 +/-
0.08(stat) (+0.18/-0.10)(sys)), and (0.63 +/- 0.02(stat) (+0.09/-0.07)(sys))
x10^20 H2-molecule cm^(-2) (K km s^(-1))^(-1) for the Chamaeleon, R CrA, and
Cepheus and Polaris flare regions, respectively, suggesting a variation of Xco
in the vicinity of the solar system. From the obtained values of Xco, the
masses of molecular gas traced by Wco in the Chamaeleon, R CrA, and Cepheus and
Polaris flare regions are estimated to be ~5x10^3, ~10^3, and ~3.3x10^4 Msolar,
respectively. A comparable amount of gas not traced well by standard HI and CO
surveys is found in the regions investigated.
