Each is marked externally by a curved groove of the neuromast system (cnm, fig. 1) which has its anterior continuation on the adjacent melonicozygomatic bone. From where it crosses the melonic-melonicozygomatic suture, this groove passes backward and upward to the center of ossification of the melonic bone; it then continues posterolaterally and downward to disappear shortly before the melonic-quadratomaxillary suture.