Two types of NS cells were observed medially in the pars intercerebralis of the protocerebral lobes ofH. triangularis. They constitute a dorso-medial and a dorso-lateral group. According to the size and staining properties with PF and CHP they are classified as ‘A’ and ‘B’ type cells. ‘A’ cells are further classified into ‘A1’ and ‘A2’ types, according to the shape and size and staining characters with PF. Only a few ‘B’ type cells as a group in the tritocerebrum were noticed. ‘B’ type cells are more common than ‘A’ type cells in the aboral third of the ventral region of the sub-oesophageal ganglion. In the thoracic ganglion the cells are large in size and peripherally distributed.