Left: spatial distribution of GMA mass (M_c) and observed GMA boundary. The ¹²CO integrated intensity map is presented with grayscale. We identify 165 reliable GMAs. Green diamonds, blue circles, and red squares denote GMAs with M_c < 5 × 10⁶ ﹩{M}_{\odot }﹩, 5 × 10⁶ < M_c < 10⁷ ﹩{M}_{\odot }﹩, and M_c > 10⁷ ﹩{M}_{\odot }﹩, respectively. The circles indicate the average radius of the major and minor axes of the observed GMA boundary. Right: classification of GMAs based on their locations in the galaxy. The background image is Spitzer 8 μm emission. The central circle and ellipse denote the area of the CNR and bar, respectively. The CNR GMAs, bar GMAs, spiral GMAs, and inter-arm GMAs are indicated with red stars, blue squares, green circles, and magenta triangles, respectively. The numbers of GMAs are as follows: 11 CNR GMAs, 21 bar GMAs, 62 spiral GMAs, and 71 inter-arm GMAs.