Abstract
The neurohypophysis of an opossum (Didelphis virginiana) and a whole pituitary from a spiny anteater (Tachyglossus aculeatus) were extracted and subjected to selected biological assays. The results suggest that these pituitaries contain arginine vasopressin and oxytocin. They resemble, therefore, the typical mammalian pituitary rather than that of reptiles or birds.