Conspicuous dust lanes define the spiral arm in the south of M31. The integrated HI line emission map shows several large cloudlike structures with sizes ranging from hundreds to thousands of parsecs, forming a spiral arm along the dust lanes (Figure 1). To investigate how such super clouds correlate with star formation phenomena, we present in Figure 2 a compilation of published data on: CO emission, dark clouds, HII regions, OB associations, and thermal infrared radiation from IRAS. The CO emission distribution is similar to that of HI and also forms large cloudlike structures. The large CO clouds P, Q, and R, which are located in the high density HI areas, have bright HII region complexes of several hundred parsecs at their outer edges. Further out large OB associations are found. In contrast, cloud B, which shows weaker CO emission, has a large and diffuse HII region which may be relatively old. This giant HII region is located in a large hole of HI and dark clouds (Brinks 1981). The IRAS maps show strong correlated thermal emission from the dust lanes. The luminosity from the star formation activity heats the dust in the molecular clouds. The local peaks at A, P, and Q in the 25 μm band, extending 200-300 pc, have revealed the existence of massive young stars embedded in the clouds.