the peak of a broader unseen component. It could be IS, but it is not seen in any of the surrounding 8 pixels, and $V_{\rm o}$ consistent with well determined $V_{\rm opt}$ ($-49.5\pm3.8$ [kms$^{-1}$]{}).

119.6$-$06.7 (Hu 1-1) Single-peaked, asymmetric profile. The well determined $V_{\rm opt}$ ($-53.7\pm3.0$) is offset by $\sim 14$ [kms$^{-1}$]{} from the $V_{\rm o}$ peak, in the direction of the extended wing.

130.4+03.1 (K 3-92) Double-peaked profile. $V_{\rm o}$ consistent with $V_{\rm opt}$ ($-61.7\pm2.8$ [kms$^{-1}$]{}).

149.0+04.4 (K 4-47) Strong, roughly parabolic profile. $V_{\rm opt}$ consistent with $V_{\rm opt} \sim -37$ [kms$^{-1}$]{} from Corradi et al. (2000).

153.7$-$01.4 (K 3-65) Double-peaked profile; spike at $V = -26 $ [kms$^{-1}$]{} is IS. $V_{\rm opt}$ is unknown.

184.6+00.6 (K 3-70) Flat-topped profile. $V_{\rm o}$ consistent with $V_{\rm
    opt}$ ($+26.9\pm4.5$ [kms$^{-1}$]{}).

359.8+06.9 (M 3-37) Strong, double-peaked profile; spike at $V = -5 $ [kms$^{-1}$]{} is IS. $V_{\rm o}$ consistent with $V_{\rm opt}$ ($-74.2\pm10.2$ [kms$^{-1}$]{}).

Discussion
==========

Detection Rates
---------------

The observations reported here significantly increase the available data on the CO envelopes of PNe. The compilation by Huggins et al. (1996) lists 44 PNe detected in CO, and only a handful of other PNe have been detected in searches in the intervening 