\begin{table}%t2
\caption{Molecular abundances with respect to H$_2$
\label{tbl-2}}
\[
\begin{array}{lccccc}
\hline\hline
\noalign{\smallskip}
\mbox{} & \multicolumn{2}{c}{\mbox{L1498}} 
& \multicolumn{2}{c}{\mbox{L1517B}} & \\
\mbox{Molec.} & X_0{\mbox{~~~~~}} & r_{\rm h} & X_0{\mbox{~~~~~}} & r_{\rm h} & \mbox{Notes} \\
\mbox{} & & \mbox{(10$^{17}$ cm)} &  & \mbox{(10$^{17}$ cm)} & \\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
\mbox{CO} & 2.5 \times  10^{-5} & 1.5 & 7.5 \times  10^{-5}  & 1.75 & \\
\mbox{CS} & 3.0 \times  10^{-9} & 1.0 & 3.0 \times  10^{-9}  & 1.15 & \\
\mbox{N$_2$H$^+$} & 1.7 \times  10^{-10} & 0 & 1.5 \times  10^{-10}  & 0 & (1)\\
\mbox{NH$_3$} & 2.8 \times  10^{-8} & \beta=3 & 3.4 \times  10^{-8}  & \beta=1 & (2) \\
\mbox{CH$_3$OH~~~} & 6.0 \times  10^{-10} & 1.2 & 6.0 \times  10^{-10}  & 0.8 & (3) \\
\mbox{SO} & 4.0 \times  10^{-10} & 1.2 & 2.0 \times  10^{-10}  & 0.9 \\
\mbox{C$_3$H$_2$} & 1.6 \times  10^{-9} & 1.0 & 9.3 \times  10^{-10}  & 0.6 & (4) \\
\mbox{HC$_3$N} & 1.0 \times  10^{-9} & 0.85 & 4.5 \times  10^{-10}  & 0.4 & (5) \\
\mbox{H$_2$CO} & 1.3 \times  10^{-9} & 1.3 & 6.7 \times  10^{-10}  & 0.7 & (6) \\
\mbox{HCO$^+$} & 3.0 \times  10^{-9} & 1.15 & 1.5 \times  10^{-9}  & 0.6 & (7) \\
\mbox{DCO$^+$} & 5.0 \times  10^{-11} & 0.65 & 5.0 \times  10^{-11}  & 0.6 \\
\mbox{C$_2$S} & 4.0 \times  10^{-10} & 1.25 & 1.0 \times  10^{-10}  & 0.8 \\
\mbox{HCN} & 7.0 \times  10^{-9} & 0.8 & 3.0 \times  10^{-9}  & 0.53 & (8) \\
\noalign{\smallskip}
\hline
\end{array}
\]
$(1)$ Factor of 3 drop for $r > 1.8 \times 10^{17}$ cm in L1498.
 $(2)$ OPR = 1 assumed, $X$(NH$_3$) = $X_0 \; (n(r)/n_0)^\beta$.
 $(3)$ E/A = 1.
 $(4)$ OPR = 3 assumed and factor of 10 drop
 for $r > 1.8 \times 10^{17}$ cm in L1498.
 $(5)$ Factors of 10 (L1498) and 2 (L1517B) drops for 
 $r > 1.8 \times 10^{17}$~cm.
 $(6)$ OPR = 3 assumed. Factors of 15 (L1498) and~5 (L1517B) enhancement 
 for $r > 4 \times 10^{17}$ cm.
 $(7)$ Factor of 4 enhancement for $r > 4 \times 10^{17}$~cm in L1498.
 $(8)$ Factors of 4 (L1498) and 2 (L1517B) enhancement 
 for $r > 4 \times 10^{17}$~cm.
\par
 \end{table}