Slit orientations superposed on HST archival V images of I Zw 18 and SBS 0335−052. The slit orientation during the MMT observations of I Zw 18 is chosen in such a way as to get spectra of the southeast and northwest components as well as of the C component to the northwest of the main body of the galaxy. The slit orientation during the Keck II observations of SBS 0335−052 is chosen in the direction perpendicular to that used by Izotov et al. (1997b), and it is centered on stellar cluster 5 (Thuan et al. 1997). The spatial scale is ﹩1^{\prime \prime }=49﹩ pc in the case of I Zw 18 and is ﹩1^{\prime \prime }=257﹩ pc in the case of SBS  0335−052.