The rostral nasal anatomy of two elephant shrews.

The nasal anatomy of Elephantulus brachyrhynchus and E. myurus shows adaptations needed for a long, mobile snout with no special chemosensory features. Olfactory and vomeronasal neuroepithelia do not extend rostral to the nasal opening of the incisive ducts. Their fine structure presents no unusual features. Separate dorsal, lateral and ventral cartilages and fenestrations in the septal cartilage permit snout flexibility. Dorsal and ventral tubular glands extend the whole length of the snout under the dermis but only release their secretions at the tip, together with the products of the nasolacrimal and lateral nasal gland ducts. These secretions may protect the bare rostral epithelium from the chemical defences of termites and ants, which are major food items. A ventral groove in the snout communicates directly with the sulcus of the incisive papilla on the rostral palate. The oral openings of the incisive ducts also lie within the sulcus. Variability in the relation of the vomeronasal duct to the incisive duct and in the presence of taste buds on the incisive papilla in the two species of Elephantulus studied here limit their value as evidence of relationships between elephant shrews and other insectivores and prosimians.