The morphology of the photoreceptors from different regions of the desert ant's compound eye is investigated by Golgi-impregnations and anterograde or retrograde haem peptide filling, combined with electron microscopy. A new type of receptor axon is described. This receptor is of the short (SVF) type but terminates in the proximal layer of the lamina (EPL-C), in contrast to the other short visual fibres, which terminate in the distal layer (EPL-A): Golgi-EM investigations show that this receptor axon belongs to the small photoreceptor R9. The receptor R9 appears to be pre- and postsynaptic to other receptor axons and to second order neurons. In each ommatidium, the axons of the two long photoreceptors (LVF) R1 and R5 (probably UV-receptors) remain paired down to their terminations in the distal layer of the medulla. The regional specialization of the retina (dorsal rim area (DRA), dorsal retina (DR) and ventral retina (VR)) is reflected by the morphology of the receptor terminals and the second order neurons. The lamina underlying the DRA consists of only one layer, an extended EPL-A; in the remainder of the eye, the lamina is trilayered. In the DRA all short visual fibres (SVF) are equal in length. The extension of the monopolar cell dendrites is restricted to one cartridge only. In the medulla, the terminals of the LVFs deriving from the DRA (R1 and R5) have more extensive arborizations than elsewhere in the eye.