PERIPHERY OLFACTORY SYSTEM IN RICE FIELD EEL, MONOPTERUS ALBUS (PISCES: SYNBRANCHIDAE), A NEW MODEL IN ANATOMY IN VERTEBRATE

Generally, olfactory organs and olfactory nerves of the left and right side in vertebrate are separate completely. Even for single nose-type cyclostomes, such as lampreys, their olfactory nerves are also separate completely. Furthermore, their anterior and posterior nostril (or choana), olfactory cavity, and cavity of olfactory accessory sac all communicate with each others, and the organs are usually open in whole. They usually have olfactory cavities, whose volume is relatively larger and steadier, and their olfactory epithelia primarily locate on one side of the cavities. Moreover, there is usually no lacuna in fish between their olfactory sacs and nasal pits.