 Strepsirrhines are defined by their wet nose or rhinarium. They also have a smaller brain than comparably sized simians, large olfactory lobes for smell, a vomeronasal organ to detect pheromones, and a bicornuate uterus with an epitheliochorial placenta. Their eyes contain a reflective layer to improve their night vision, and their eye sockets include a ring of bone around the eye, but they lack a wall of thin bone behind it. Strepsirrhine primates produce their own vitamin C, whereas haplorhine primates must obtain it from their diets. Lemuriform primates are characterized by a toothcomb, a specialized set of teeth in the front, lower part of the mouth mostly used for combing fur during grooming. Often, the toothcomb is incorrectly used to characterize all strepsirrhines. Instead, it is unique to lemuriforms and is not seen among adapiforms. Lemuriforms groom orally, and also possess a grooming claw on the second toe of each foot for scratching in areas that are inaccessible to the mouth and tongue. It is unclear whether adapiforms possessed grooming claws.
