嗅囊具发达的初级嗅板，但无次级嗅板。
The olfactory sac has well-developed primary lamellae , but no secondary lamellae .
嗅囊的长径与短径基本上是随体长的增长而呈直线的增。
The long and short diameters of sac generally increase linearly with the increase of body length .
嗅囊嗅囊嗅囊