The larva swims by a ri ig of cilia, which corresponds with the praeoral circlet of a Trochosphere.
In the centre of the praeoral lobe is a tuft of cilia.
A recently described species, Dolichorhynchus indicus, characterized by the great length of the praeoral lobe or snout, has been dredged in the Indian Ocean.
The cephalic region includes the rostrum or praeoral [[Right Fig]].