1. In the superfamilySpiruroidea, there is a difference in structure of the oesophageal glands between forms, in which the oesophagus has no distinct constriction between the anterior and posterior portions, and forms, which possess such a constriction. In the former group, all the three glands are confined to the posterior portion of the oesophagus and belong to a branched tubular and multinuclear type of whichPhysaloptera clausa andSpirocerca sanguinolenta are representatives. In the latter group, only the two subventral glands are confined to the posterior portion of the oesophagus and belong to a branched tubular type, whereas the dorsal gland extends to both the anterior and posterior oesophagus portions, and belong to a non-branched tubular type, and furthermore, all the three glands are mononuclear:Camallanus intermedius is a representative. 2. In the superfamilyFilarioidea, the structure of the oesophageal glands differs between forms, in which the oesophagus has no distinct constriction between its anterior and posterior portions and no enlargement at the anterior end of its posterior portion, and forms, the oesophagus of which has likewise no distinct constriction between its anterior and posterior portions, but has an enlargement at the anterior end of its posterior portion. In the former group, all the three glands are confined to the posterior portion of the oesophagus and belong to a branched tubular and multinuclear type:Dirofilaria immitis is a representative. In the latter group, all the three glands are also confined to the posterior portion of the oesophagus, but the two subventral glands extend anteriorly only to the posterior margin of the enlargement of the posterior portion of the oesophagus, and furthermore, all the three glands belong to a tubular and mononuclear type:Dracunculus houdemeri is a representative. 3. The oesophageal glands in forms where the oesophagus is divided into an anterior, and a posterior, portion without a constriction at their junction, and also without an enlargement at the anterior end of the posterior oesophagus portion are found similar in both superfamiliesSpiruroidea andFilarioidea.