Further, two distinct types of otocyst can be recognized in the Hydro medusae; that of the Leptolinae, in which the entire organ is ectodermal, concrement-cells and all, and the organ is not a tentaculocyst; and that of the Trachylinae, in which the organ is a tentaculocyst, and the concrement-cells are endodermal, derived from the endoderm of the modified tentacle, while the rest of the organ is ectodermal.
We then find the typical otocyst of the Leptomedusae, a vesicle bulging on the ex-umbral side of the velum (figs.
The right otocyst is seen at the root of the foot.
Accordingly the difference is one of position of the otocyst and not of its nerve-supply.
P, Pedal ganglion with otocyst attached.
Two stages in the development of the otocyst can be recognized, the first that of an open pit FIG.
In Filibranchia and many Protobranchia the otocyst (or statocyst) contains numerous particles (otoconia).
U, The otocyst attached to the Ctenidium (gill-plume).