  A faint $I_{\rm 170}=4$ MJysr$^{-1}$ bipolar globule was discovered with the
ISOPHOT 170 $\mu$m Serendipity Survey (ISOSS). ISOSS J 20246+6541 is a cold
($T_{\rm d}\approx 14.5$ K) FIR source without an IRAS pointsource counterpart.
In the Digitized Sky Survey B band it is seen as a 3\arcmin size bipolar
nebulosity with an average excess surface brightness of $\approx 26$
mag/$\square $\arcsec . The CO column density distribution determined by
multi-isotopic, multi-level CO measurements with the IRAM-30m telescope agrees
well with the optical appearance. An average hydrogen column density of
$\approx 10^{21}$cm$^{-2}$ was derived from both the FIR and CO data. Using a
kinematic distance estimate of 400 pc the NLTE modelling of the CO, HCO$^+$,
and CS measurements gives a peak density of $\approx 10^4$cm$^{-3}$. The
multiwavelength data characterise ISOSS 20246+6541 as a representative of a
class of globules which has not been discovered so far due to their small
angular size and low 100$\mu $m brightness. A significant overabundance of
$^{13}$CO is found $X(^{13}CO) \ge 150\times X(C^{18}O)$. This is likely due to
isotope selective chemical processes.
