Nasolamia differs externally from all other carcharhinids in having very wide, transversely oriented nostrils placed close together so that the internarial width is only slightly greater than the width of each nostril. Cranial differences, which are in the ethmoid region and separate Nasolamia from all other carcharhinid genera except Prionace, include not only a narrow space between the nasal apertures, thus reflecting the external condition, but also the long axes of the nasal capsules being nearly parallel to the longitudinal axis of the cranium rather than diagonal to transverse to it. In other features Nasolamia comes closer to Carcharhinus than to any other carcharhinid genus.