The heteropteran cephalic endoskeleton is difficult to study in dissections, due to its small size and to the delicacy of many of its membranous components. These difficulties are less of a handicap in dissections of the giant water bug Lethocerus (Belostomatidae), and it is possible to observe, in this insect, details of the salivary pumping apparatus which are difficult or impossible to see in smaller bugs. This apparatus consists of a cup-shaped, two-layered pump, two afferent ducts from the salivary glands, and an efferent duct. The latter runs from the pump to the tip of the hypopharyngeal lobe, and leads into the salivary channel formed by the apposed maxillary stylets in the labium.