Spectra of Cloud 21. Positions are indicated on the x and y axes as offsets in arcminutes and each box represents 30″. ¹²CO is in black, ¹³CO in red, HCO⁺ in green and HCN in blue. The velocity scale goes from −106.5 km s⁻¹ to −97 km s⁻¹. The temperatures scales are −.7 to 7 K for ¹²CO, −.14 to −1.4 K for ¹³CO, −.02 to .2 for HCO⁺ and for HCN. The HCN line (only central component shown) has been multiplied by 9/5 so that the line intensity represents the total line flux for comparison with other species. The ¹²CO and ¹³CO spectra have been convolved to the same angular resolution as the HCN and HCO⁺.