11. The plica sublingualis is also prominent. 12. The plica mediana is usually made of cartilage and attaches the sublingua to the underside of the tongue. 13. The plica themselves are remnants of the fetal stage of development where the knee is divided into three compartments. 14. The plica fimbriata is highly developed and specialized in lemurs, and makes up the majority of the sublingua. 15. Lemurs also have a third eyelid known as a nictitating membrane, whereas most other primates have a lesser developed plica semilunaris. 16. The pitch indicated by the plica depends on the pitches of the note it is attached to and the note following it. 17. If the interval between the main notes is a third, then the plica tone fills it in as a passing tone. 18. These webs, located between each set of digits, are known as skin folds ( interdigital folds or plica interdigitalis ). 19. The point where the plica sublingualis attaches to the rear floor of the mouth marks the location of the submandibular salivary glands. 20. The tarsier has a distinct plica mediana and its plicae fimbriatae are large and stick to the entire underside of the tongue.
