The posterior subclavian ganglion of the newt Triturus viridescens consists of a central zone of adrenal or interrenal cells and an outer cortex of chromaffin cells and sympathetic ganglion cells. Interrenal cells contain abundant large clear vacuoles in the cytoplasm and mitochondria with tubular cristae. Two types of chromaffin cells were observed: cells containing opaque granules, 1500 Å in diameter (norepinephrine), and cells containing moderately dense granules, 2600 Å in diameter (epinephrine). Both types of granules are present in a few cells. Sympathetic ganglion cells and their efferent nerves contain vesicles, 750 Å in diameter, with dense cores. Small unmyelinated nerves are located between chromaffin cells or between ganglion cells and their satellite sheaths. In synaptic regions, spherical or oval clear vesicles are abundant. Large bundles of a few myelinated nerves and many small unmyelinated nerves occur between the cellular elements. Axons are enveloped by Schwann cells and the large nerve bundles are loosely enclosed by a connective tissue sheath (endoneurium). Melanophores or pigment cells and connective tissue elements occur in the cortex of the gland.