  We present the results of a molecular line survey of the extreme carbon star
CRL 3068. The observations were carried out with the Arizona Radio Observatory
(ARO) 12m telescope and the Heinrich Hertz Submillimeter Telescope (SMT) at the
2mm and 1.3mm atmospheric windows. The observations cover the frequency bands
from 130--162 GHz and 219.5--267.5 GHz. The typical sensitivities achieved are
T_R<15 mK and T_R<7 mK for the ARO 12m and SMT, respectively. Seventy two
individual emission features belonging to 23 molecular species and
isotopologues were detected. Only three faint lines remain unidentified. The
species c-C3H, CH3CN, SiC2, and the isotopologues, C17O and C18O, HC15N, HN13C,
C33S, C34S, 13CS, 29SiS, and 30SiS are detected in this object for the first
time. Rotational diagram analysis is carried out to determine the column
densities and excitation temperatures. The isotopic ratios of the elements C,
N, O, S, and Si have also been estimated. The results are consistent with
stellar CNO processing and suggest that CRL 3068 is more carbon rich than
IRC+10216 and CIT 6. It is also shown that the chemical composition in CRL 3068
is somewhat different from that in IRC+10216 with a more extensive synthesis of
cyclic and long-chain molecules in CRL 3068. The results will provide valuable
clues for better understanding circumstellar chemistry.
